Seasons changing

Everything is back up and running, and I've notched a few more successful outings.  I had my first windy trial this week.  It's a small lake so waves were not bad, but it was maybe 25 mph gusts.  After getting so used a catamaran, I admit it was a little unnerving at first to feel the wind rock the boat.  By the end of the day, I was much more comfortable.  It will still take some getting used to, especially when I do hit some bigger swells.

All things considered, I would have to say the project has been quite a success.  There are a few bugs to work on, but I've had fun on the times I've been on the water.  Hopefully I don't make anything worse when I take it apart to sand and varnish in the spring.  I'll work on some of the bugs before I put it back together.

The first priority will be the gearbox.  It is currently fine for cruising, but not for anything needing more power.  I suppose I am glad I opted for less expensive straight bevel gears rather than spiral gears.  If the box isn't stiff enough, the more expensive gears would have met a similar fate: worn, rounded teeth.  I have some thoughts on reinforcing the housing with cross pieces and also cover plates with a lip on the edges to help prevent pedaling forces from flexing the housing.  If there is an improvement, maybe then I will upgrade to spiral gears.

Next up is the prop.  There is a yet unexplained difference in speed at a given blade pitch compared to calculations, so I have had to modify the blades to make things work well enough.  I suspect my first attempt will simply be to remake the blades and attempt a more accurate foil shape when grinding.

I might also go ahead and replace the full shaft, I'm not sure.  It isn't that expensive, so it might be nice to try one that wasn't accidentally bent before assembly.  I'm still undecided about the drive leg.  There are several options to increase the strength of the chain loop.  The current setup can handle more than the gearbox, and I think it would be fine for distance race speed, just not short full sprints.  I might also try a leg fairing that slides over the drive leg tube rather than move with it.  The steerable prop is nice and it works well, but I think it limits my options on making the chain loop stronger.  I doubt I will decide until spring.

On the boat side, I don't think there is much I would change.  During the design I wasn't sure how far I would place the gearbox from the seat to fit my height.  My other boat has a profiled recumbent seat and this one has a sharp angle, so comparing the two was difficult.  Now that it is set up, I can see I could have shortened this about 3 inches and decreased the windage of the gearbox support.  There might be a few other changes to reduce windage, but it all amounts to fine tuning.  I have modified the stabilizer mount: reattaching the two halves and I also added a cross pin between the vertical pivots to reduce flexing.  It has made a big difference, so for now I will leave this alone.  I really like the vertical adjustment and the ease of setup when launching.  I imagine starting over I could shave off some weight, but it would again be minor changes.  As I mentioned before, in a new boat I would probably make the stabilizers out of foam sheet and also reconsider the weight of cloth in some areas.  It might all amount to about 5 lbs.

Last but not least, repurposing the trailer for the cat works OK, but I will eventually make or buy a better setup.  Ideally something small I could stow on the boat, so I wouldn't even need to walk back up the shore when launching.

In the mean time, the garage needs to be turned back into a garage.  I don't think I would get much support for my hobbies if it meant scraping frost off the car windows.  I've already put the cat up in the rafters and cleaned up my tools and mess.  Hopefully I can get out on the water again before the cold water deters me, but there is a chance this is it.  At least the outing this week was a nice sunny (but windy) day with fall colors.

Hopefully some of the people reading have a nice warm shop or are just getting ready for summer!  If you have a project, it would be great to see it.  Turns out this blog stuff is pretty easy...

Hydrobowl outing

I've been reading about Hydrobowls for years and was hoping I would finish in time to make it to the event about 6 hours from Minneapolis.  It is a multi-discipline race with overall winners based on points over 5 races.  It is intended to be a measure of overall performance, and I would say it does a reasonably good job at it.  The races are a 100m flying start sprint, a slalom, a 100m drag race from standstill, a 2k criterium, and a static thrust test.  I wish that there was a race where a fast boat could go fast over a distance without the need for agility, but I suppose this is because I found that my boat was slowest cornering boat of the group!

 It is an informal competition, but several of the racers have been going for years, or decades, and have tailored boats to the event and refined over the years.  My boat held it's own, but the drive definitely suffered some wear and tear.  Before the start I had adjusted the angle of the prop blades to increase the pitch - the distance you are supposed to go each rotation.  I ended up with a better feel on the sprint, but the long distance events had me wishing for a faster cadence.  I suspect I will go back to somewhere in the middle.  The final points totals are pending, but I was somewhere in the middle.

The course is a 100m set of buoys, with two parallel rows.  The rows are about 20 meters apart.  The slalom weaves between the 5 or so intermediate buoys along the 100m, but you have to span the 20 meters each time.  The 2k criterium is 8 1/2 laps around the buoys.  This basically means you need a boat that can corner with a 10m turning radius to have any success on these 2 of the 5 events.  I would say my boat is more like 20-25m radius.  This means the slalom needed some reverse thrust with a paddle to make the turns, and the criterium for me was a lot longer than for everyone else because my oval was about twice as wide as the buoys.  My boat turns just fine for cruising a lake, but the 20 degree limit on the rudder rotation means it can't compete on agility.

The drive showed some signs of trouble.  I had anticipated both, but there is no good way to know for sure until you just try it.  The gearbox skipped teeth in the gears while sprinting.  This could be both due to the large size of the housing and the ability of it to flex, but I suspect it is also a result of the bearing bores coming back a little oversize from the shop.  The shop ran the reamer at a high RPM and this caused vibrations and a hole that was a little too big.  I tried to close it a little by peening edges with a punch to close the opening a little.  But it is still not a great fit and allows the output shaft too much play.

Also, I have been using the 25 pitch chain for years without issue on my cat, even after sprints, but this older drive is geared a little higher and also uses 12 tooth sprockets on the prop shaft rather than 9 tooth for the new boat.  It doesn't seem like a huge difference, but it means the chain has about 25% more tension during the same pedal force.  Given the demands when sprinting, this pushed the boundaries a little too much and the chain started to stretch and get too loose and could get jammed up.  Before I could adjust it properly I limped through the slalom and drag race.  I wasn't too surprised; I had debated sticking to 12 tooth for a while.  I would say the drive would manage just fine for years under normal use, just not all out sprints.

Hard to say where I will head from here in terms of design.  The Hydrobowl's future is uncertain since the organizer moved away from the area.  It is a fun challenge to tackle an all around boat for these events, but it is hard to say if the events will happen again soon (unless I host one in Minneapolis!).  Otherwise I could throw on a new chain and cruise the lake quite content with the way thing are.

This is with the caveat of fixing the stabilizer mounts.  As I mentioned, I was concerned about the stiffness after splitting the bracket into two halves.  This was a well grounded fear.  I've found that the vertical supports behind the seat will rotate slightly and also flex the bracket such that the long supports angle 5-10 degrees (estimating) towards the stern.  This means the stabilizer drags at an angle and plows the water, causing more drag and more flexing.  During the drag race I crossed a wake and this set off this feedback loop until I almost went for a swim.  I will definitely modify this.  I am very happy with the vertical adjustment part, but I will join the halves into one.  I will also remove the pivoting pieces from the bracket and use a short horizontal double ended nesting tube on the same bracket that connects to both long arms.  This will eliminate the flexing.  In order to achieve my goal of self contained stabilizers for walking to the lake, I think I will add separate short nesting tubes pointing towards the stern and I can remove the arms from the "in use" tubes and click them onto the "transport" tubes.  My timeline for this is uncertain.  Fall approaches and it is time to build up a good store of outdoor memories to last through the winter.  Fortunately the overall boat is quite sound.  I can work on the small stuff like mounting arms and gear boxes in my basement over winter.  I'm not sure I will, but at least I could.  Come spring, I will get the boat sanded and varnished and actually "finished".  Hopefully I will post some more nice cruising photos this month, and then I'll have to wait and see.

Maiden voyage!

I had my first trials yesterday and today.  Generally, they were successful.  I had a few bugs to work out with the steering cords and chain tension, but I was on the water doing nice laps after a few false starts.  A priority will be grinding the prop to add the lift from a proper profile.  Also, I may adjust the pitch as I was spinning out on the pedals before getting to max effort.  A future priority will be sealing off a greater portion of the stern hull.  You will see the stern sits low due to water that enters a fairly large drive leg stern partition through the drive leg opening.  This will be an easy modification once I take the time to work on it.  It's been a long day, so I apologize for a lack of a storyline on the trials.  This will have to be a photo post for now.

The rest of the drivetrain

I can say now that the scope of my summer project has been changed slightly.  The boat is ready to hit the water (it already has actually, but I'm behind on posts), but it is not finished.  I have yet to do any final sanding on the hull; and no varnish yet, either.  I will do a few more things to prepare for the Hydrobowl this coming weekend, but I will focus on the prop and steering.  Varnish will probably wait until spring.  Right now I want to enjoy it for a few weeks before the weather turns.  And winters are long here...

The final area of the boat I have not focused on in posts is the rear end of the drive.  It is a variation of the flex shaft design Rick has refined lately.  I like a lot of advantages of the "standard" flex shaft, but I have had an idea in my head for a few years, and I really wanted to see if it would work.  Now that it is mostly done, it is easier to explain.  I am using a flexible shaft, for the full length of the boat, but it does not extend below the hull as in Rick's system.  I am running the shaft under the seat and along the deck line to the stern where it joins with a separate drive leg.  The drive leg uses a 1/4" pitch chain common on twisted chain drives, but the chain does not need to twist since the gearbox has already changed the pedal motion 90 degrees.

After a lot of searching I was able to find inexpensive stainless 9 tooth sprockets for this chain.  The max shaft size was 1/4" but I wanted to drill them out for 3/8" shafts.  This meant there wasn't enough material left in the hub for a cross pin, so I found a local bicycle fabricator who silver soldered the sprocket on, and it looked pretty secure.

I realize now that my photo collection is incomplete for the drive, but I can add photos later if there are any requests.  The shafts are mounted in stainless bearing and I leave it all open to water.  This is the same approach I used on my first boat, it is 7 years old now on the original parts with no corrosion on the stainless.  Good enough for me.  The chain runs through a 1 1/4" OD aluminum tube.  This is the smallest possible size drive leg I could figure out how to make.  The round tube is welded to a 1 1/4 rectangular tube which houses the prop shaft and bearing.

The drive leg tube has a foil fairing based on precise plywood pieces cut from the CNC batch.  I sandwiched foam and wood to maintain and accurate shape.  I precut a (slightly undersized) hole in the wood pieces, and once this was all together, I cut it into front and back halves along this hole centerline.  I then wrapped sandpaper around scrap tubing and sanded away the foam from the inside.  This allowed me to glue the fairing to the drive leg and essentially not add any width to the tube except for a layer of glass cloth.

 One of the key reasons this general design appealed to me is that the prop is steerable.  The drive leg tube nests inside a square tubing with flange bushings.  The drive leg tube has a slot for the upper drive shaft, and the clearance in the slot allows for about 20 degrees of rotation each direction.  It can be increased slightly if needed.  The square tubing is bolted to the inside of the hull.

 One of the primary concerns with drive legs is weed catching and collisions.  Generally, these are not issues where I will be boating for the near future, but I added a small strut to help deflect weeds and ramp over obstacles if I hit something.  I will eventually file this strut to a nice profile.  The twist isn't ideal because it will add slight drag, but it is the fastest approach for now.  The bottom of the strut is bolted with a shoulder bolt to the drive leg bottom so the leg can pivot about the strut.

There are plenty of downsides to this design relative to using only a flex shaft under water, and I was aware of them and willing to try it anyway.  I accept it is not an ideal solution for most home brew boats.  But there are a few advantages, and I will focus on these.  Because the shaft only has a small amount of curve, I can use 3/4" diameter (.058" wall) tubing the full distance, and maintain the best possible torsional stiffness with a minimum of weight.  I calculate the shaft at about 44 Nm/rad stiffness, significantly higher than cases where a thinner shaft is used underwater to accommodate the increased bending.  There is no need for a rudder of any kind, and the strut fairing can be more effective since it is not surface piercing.  This is in addition to the steering from prop thrust.

Beaching is more of a gray area.  The strut is currently fixed so it will hit when beaching.  The lake I am on is deep, so this is not a concern for me.  The downside is that the strut is fixed, the upside is that the shaft is protected so beaching will not bend the shaft, which can happen when not using spring steel.  In fact, the second reason this design was appealing was that I intended to make the drive leg beach-able.  My idea was to detach the stern portion of the hull and add a transom.  Then I could use the deck panel or a portion of it to flex up with the shaft.  It would essentially be a long hinge flexing/pivoting with the shaft.  Since the shaft does not flex a large degree in steady state use, it could accommodate more flex with beaching.

In the end I decided this would take more time, and I would prefer to proof the general concept and reliability before I cut into the boat.  If I decide not to continue with this drive leg it is currently easy to undo.  If it works out for a year or two, I can still use it as a test bed for a steerable and beach-able flex shaft drive leg.

The complete drivetrain is very low friction.  I can easily rotate the shaft with my fingers and maintain motion for about a prop rotation; however, I managed to bend the shaft slightly during my experimenting and it has a slight pulsing as it rotates due to this bend, so it always stops at the high resistance point when I try to spin it.  It is not something I can feel with my legs.  I replaced my original bushings with ball bearings since they are protected from water.  I would consider it relatively light weight as well.  The drive leg adds weight but there is no rudder and the shaft has only 12 inches of steel.  In the end, the full assembly with full shaft, shaft bearings, drive leg and rudder control is just under 4 lbs.

Seat back finished, prop started

As I have mentioned, reworking the seat back has been one of my most time consuming duplicated efforts.  My original design had an integrated headrest with a few extra panels to create this.  Rick and Mike decided against this in the end for various reasons, including ease of indoor storage, so I too revised this design and cut a new top panel with no head rest.  I had this completely built and ready to put on the hull when I decided it was not a good long term solution so I would try the replacement now.  I decided to cut the new panels out of cardboard because I barely had enough scrap to use and I could not afford any mistakes.  In the end I am happy with the result and would definitely use this shape again.  The hatch in this new section is to be fastened with wood screws and is only for maintenance access, not storage.

The gearbox fits in nicely.  You might notice that the hole pattern is not perfectly parallel with the slot.  I don't think the software is well suited to help a designer verify things like angle between two surfaces.  I am quite inexperienced using it, so if there is an easy way, I don't know how, and the end result is my accuracy was off a quarter inch or so.  Fortunately the slot was oversized and still had clearance.  Once everything was together I could see that the crank arms had about an inch of clearance between the inside of the arm and the boat.  It is much more than I needed and it makes my feet farther apart than necessary, but at the time I wasn't sure how far the arms would slide up the tapered shaft, so I erred on the safe side.  Now I would cut the shaft much shorter.  Incidentally, I also swapped my 170 mm arms for 145 mm arms (I had ordered both at the start to be safe).  I have pretty big feet, and it will be very close to hitting my heels on the boat.  Someday I will try, but I didn't want delays on my first outing.

I also started my prop using the same folding hub design Rick has been using.  In fact, he provided a part I could try.  I bent the blades per my design spec, but I did not have time remaining to grind them before we needed to pack up for the holiday weekend.  I assembled them to the hub and to the shaft and that will have to do for the first trial.


Time up to this point:  My motivation to track accurately is fading, but I am at around 150 hours, including around 20 hours of reworks.

Stabilizer mounts finished

As it turns out, as I wrote my last post, the seat post clamps I needed to finish the stabilizer mounts were sitting on our front porch.  I was able to add these to the arms yesterday.  I needed to file about 1 mm of material off of the tube to leave space for the lip on the inside of the clamp.  This usually serves to keep the clamp from slipping down the seat tube.  Here it also helps keep it in the correct position.  I also drilled a small stress relief hole opposite the 3/8" snap button hole and used a hacksaw to create a slot about 1 inch long up to the small hole.

I got the clamps in position and I would say they work well.  They will keep the parts from moving with regular motion of waves, but they can still be moved since the lever arms are so long.  With the weight of the clamps, the full assembly is pushing 13 lbs, but there is no extra stuff on the hull except for thread inserts.

After getting the full assembly together, I became a little concerned that my last minute change to allow split mounting and independent height adjustments might have compromised the strength more than I expected.  The photo here shows the two halves joined together.  There are a series of holes 3/8" apart to allow about 1 1/2" of movement in each direction.  I guess if I had planned ahead and knew the direction of prop rotation I really would have only needed to adjust in one direction, but there was enough space for both.

The two halves create a "V" that will nest with the fairing on the seat back.  The long slots will allow overall height adjustment with 4 knobs threaded into thread inserts in the seat back.  Now that the full assembly is together I have a better appreciation of two things.  First, the stabilizers are a little heavier than I was expecting at 5 lbs each.  This doesn't seem like a lot considering I used a minimum of epoxy and glass, but the second thing I have a better appreciation for is the feel of hanging 5 lbs on the end of a 3 ft lever arm.  It would have been an easy calculation, but I admit it wasn't something that jumped out at me having never used a boat with outriggers before.  Needless to say now, the long lever arm causes the bracket to flex quite a bit at the two fasteners holding the halves together.  Fortunately, I did fiberglass inside and out of both bracket halves so the panel joints will be secure.  This flexing should be improved a bit when there are 4 extra fasteners holding everything to the hull, but it could still be an issue.  I guess worst case, once I arrive at the offset I would like, I can re-glue the halves together permanently in this position.  I'll have to try it to see.

Overall, I like the ease of folding the stabilizers up behind the seat.  I am hoping that I can also raise the bracket high enough to put the stabilizers on top of the rear deck, otherwise they will hit the sides a little and I will need to bungee them in place so things don't bump around.  With the 4 fastener knobs holding the whole thing on, if I do need to cartop the boat, I can easily remove this weight and save my back when I lift the 55+ lbs I expect the rest of the boat to weigh.


Time to this point (everything including repeating steps): 120 hours

Details, details...

The devil is in the details with boats as much as with anything else.  I have made quite a bit of progress on the front end, where it turns out there are lots of small details.  I have finished off the hand holds.  I have made the little covers for the gearbox.  One covers the opening to slide in the gearbox into the slots, and another covers a small access to the first shaft bushing and the shaft collar to make leg length adjustments in the shaft coupling.  I suppose if I had used a top mounted gearbox, these would not be necessary, but I still like the look.  I imagine once I have forgotten about the extra few hours it took, I will be happy I did it this way.  

I've also added threaded inserts to two places for standard bicycle water bottle cages.  One set is on the front panel adjacent the forward hatch opening.  The other is on the top between the gearbox and seat.  For these bottle bosses and small access panels, I used small brass thread inserts.  It turns out I had to modify them to make them secure in wood without spinning free in moderate torque.  I think my modifications have worked and now that I chased the threads with a tap, the fasteners fit in easily and shouldn't create much torque. 

I have also nearly completed the hatch coaming for the forward hatch.  It has 10 small magnets seated into the material.  There will be matching pairs in the cover and a thin gasket.  I'm hoping it will seal reasonably well, but the fact that the cover is curved is not in my favor to achieve anything watertight.  It's something to consider for a future refinement, but I think the only time water will reach this high on the deck in any amount will be in a capsize, and then the inside might get wet, but shouldn't get swamped.  However, I'm not sure I can realistically get the actual hatch cover done in the next week, which is my unofficial deadline.  We have a trip next weekend I would like to use as a maiden voyage, and if all goes well I would like to go to the Rockford Hydrobowl the weekend after and "compete" against other boats.  It is a race, but with equal parts informal fun.  I can tape up the opening if I am worried about flipping.  As long as I can enjoy a few runs before winter, I can get it 100% finished later.

Once the last few coaming gluing steps are complete, the remaining forward deck and seat will be ready for final epoxy fill coats, and then finishing.  As far as the rest goes, I have the stabilizers painted and complete and the brackets and beams painted and only waiting for the seat post clamps I decided to go ahead and use to eliminate all slop from the moving parts.  This post should come soon.

I have also spent a considerable amount of time reworking the back of the seat.  I was originally hoping to use this space as a large cargo space with a hatch in the seat back behind the cushion, but I would say in the rare case that the front cargo space won't fit what I need, I can easily bungee a dry bag to the back of the seat.  Also, this arrangement added significant windage, and lastly, the panels fit together with a lot of twisting to accommodate the multiple angles of the seat back.  This proved very challenging to fixture during gluing and it is not something I would like to repeat.  Since I hadn't fit the rear fairing to the hull and was dreading this as well, I decided I would just try what I wish I had done.  So far so good, but it isn't done yet.

Because of my reworking, the time tracking is more complicated.  I'm up to about 110 hours, but 10-15 of those have been repeating steps or making changes that could now be done up front at the CNC shop.  I'm getting close, but I had hoped the whole process would be about 100 hours.  I imagine I am in good company of those who underestimate the time it takes to make a new design of a wooden boat.

Stabilizers finished

I've been feeling more productive this week, but it is still a lot of effort to finish up what seem like "accessories".  Right now the stabilizers are essentially ready for finishing.  I will add a final epoxy coat and then a final sanding.  I am leaning towards painting the stabilizers to save some time vs varnish.  It will be the first time I have ever painting anything after making it in wood, but perhaps it's a good time.  I am starting to think that the stabilizers should be made from laminated foam core (Rick uses Klegecell).  I have weighed the wooden stabilizers and they come in at 5 lbs each, 6 lbs with the mounting arms and brackets.  It would be a significant weight savings using foam and the panels all fit nicely on one sheet anyway.  In this case, they would be painted, so maybe I should see if it looks good.

The stabilizers were fabricated in a similar way as the main hull, but I was willing to save some weight on the lamination steps since it is unlikely that the stabilizers will have any major impacts and need the same strength as the hull.  For these panels, I coated the inside with epoxy but no fiberglass.  I added a fillet to the inside corners but no glass tape.  The outside was fully laminated, but I used 4 oz cloth rather than 6 oz cloth.  It is the first time I have tried this weight.  It is noticeably thinner, so I imagine it took less epoxy to wet it out.  I don't know if this was significant.  I think it might be appropriate to use this weight for other inside areas, maybe the inside of panels above water line, again since there is little risk of impact, but it would still seal the wood and improve stiffness.

I have glued the mounting tube studs to the stabilizers.  These go through the top and nest into a piece of plywood glued to the bottom.  I assembled the mounting arms and held them perpendicular to the stabilizer while I drilled a 3/8" hole for the snap button.  The holes were a very tight fit, so I was able to slowly file the hole larger until it was just big enough to fit the button without any binding.  With this minimum clearance, it results in about 1" of play at the end of the 3 foot arm.  I think this will be acceptable since these will be primarily skimming the water.  I will just have to try them out.  If it does bother me I can add a slot to the outer tube and a clamping collar, probably something like a seat tube clamp on a bike. 

Total time to this point: 90 hrs

Stabilizer mounts

I have had another rather unproductive week.  Since our son was born late last year, my free time is generally limited to nap times on weekends and after bedtime.  It is also limited to the times when I am not sick with the various germs he brings home from daycare.  This past week we shared multiple rather tenacious viruses.  Slowly we are getting back to normal.

I have started working from the gearbox to finish up the hull, but I had run out of epoxy and needed to wait for more to arrive.  I had a little left of a different brand, so I am using this for the stabilizers so I can avoid mixing.  The boat will be a trimaran, but the stabilizers will be positioned to barely touch the water in calm conditions.  I am using a slightly different stabilizer mounting design from previous versions of Rick's V15.  There are a few use considerations guiding the design.  One is that I live near enough to a lake that I can walk there using a dolly and car topping will be infrequent.  This means I would like to keep all the pieces together for the walk over, and have a very easy assembly process.  My boating outings are also limited to short windows, so every minute saved in setup is an extra minute on the water.

To keep the pieces together I am using a some nesting tubing so the stabilizers can be rotated out of the way.  The snap button will have two positions, one for transport and one for use.  The nesting sections will be vertical and will be joined by a 3 ft horizontal tube.  A secondary benefit to having a vertical mount is this provides a few extra inches of wave clearance.

The fiberglass tubes are all purchased from a small kayak paddle manufacturer.  The nested tubes are originally made for two-piece paddles, so the fit is very good.  The mount at the main hull will be located at the vertical edge of the seat back fairing.  This will allow for height adjustments based on rider and cargo weight.  I have also made a late modification to use a split mounting bracket so each side has independent height.  Based on trials from Rick, he points out that the propeller torque is high enough at cruising speed that the boat can list slightly.  One way to offset this is to lower the stabilizer on one side.

 So far, I have used a small drum sander drill attachment to create the "fishmouth" shape on the tube ends.  I used gel epoxy and set up everything to bond parts square.  Afterwards, I used scrap wood for gussets and applied fillets and glass tape over this for reinforcement.  It should hold up.  I will be painting these components, including the brackets.

Since the last post, I have also stitched and glued most of the stabilizer panels and the bracket panels, but I will put these photos in a later post.

Time up to this point: 75 hours

Joining the forward deck

It feels like progress has slowed because a lot of the work has gone to joining small pieces and reinforcing internal seams that won't be visible, but on the upside it is looking a lot more like a boat.  I finally was able to join the rest of the forward deck onto the main hull.  Using stitches wasn't realistic because it was going to rest on the edge of the splash guard where panels come together roughly in a Y shape.  It took some creative use of clamps and a few borrowed hands to help temporarily align things, but the pieces did get persuaded into position.  I used gel epoxy on these seams as well.

The tricky part came next.  The footwell areas need to be securely bonded to the hull because it is possible I will stand directly in these areas.  This meant applying glass tape to the inside seams.  Fortunately, I did not assemble a small vertical panel on the gearbox mount, and this allowed access to the underside.  It is also fortunate that I have long arms.  In this case, I did not want to have to sand a cured fillet all the way inside the hull before applying the tape, so I did both in one step.  I applied the fillet, mostly blindly, with a syringe and then smoothed it out.  Before the fillet cured, I soaked the tape in epoxy and rolled it up.  I unrolled the tape, again mostly blindly, and smoothed it out.  The advantage of combining these is that you can smooth out any lumps in the fillet while smoothing out the tape, rather than beforehand by sanding.  There is a risk it could become an even bigger mess if something goes wrong, but it is a good option in some cases.  I could shine a flashlight inside from behind the seat when I was finished and confirm that the tape was roughly in the right place and was free from large bubbles.  Once the tape was cured, I reached back inside with sandpaper and gave the tape edges a quick sanding.  This is too prevent any cuts if I need to reach there in the future.  Not surprisingly, the rough edges can be as sharp as glass.

A recommendation for the future is to evaluate a similar design but to attempt to reduce potential windage issues from the large central panels.  It should be sufficiently rigid to use an L shaped rectangular beam that extends from the seat to the gearbox and angles down to the deck.  This would leave more open area.  I think it could also create useful open storage area for water bottles and a mesh pocket or similar.  I doubt I will modify this one, but I will think it over.

Now it is on to more small details.  I am creating two hand holds on the sides of the seat.  I will add small half-round wood trim to the bottom for a smooth grip.  At some point I will figure out a way to place a rudder control inside this recess so it is easy to reach without repositioning my hands too much.  This will probably wait until the end.

I will also need to figure out a way to close up the main forward deck opening with a hatch.  I've been reading about some nice wooden hatch covers secured using rare earth magnets.  Maybe I will try this, since tension straps won't be very practical in this position.

 Time up to this point: 62.5 hours

Forward deck and gearbox mount

The chronology is getting a little fuzzy, but since the last boat post, I have spread on two fill coats of epoxy to the outside main hull.  It looks like I managed to avoid making a big mess of anything on the outside.  I can definitely see improvement with each of my last boats.  The next general step is to complete the remainder of the forward deck.  This includes the footwell panels, the gearbox mount and the seat bottom.  I can then work my way from the gearbox along the driveshaft and complete remaining panels as I go.  

I tried to minimize the number of panels, but this does mean that there are some aggressive curves to form transitions.  

It has taken a significant amount of time to glass each of the individual remaining panels separately.  It also creates a lot of waste as there will be cloth trimmings and left over epoxy.  If I try this again, I will hopefully negotiate to pre-laminate a full sheet of plywood and have the CNC shop cut the small panels all out of this sheet.  

 

I am making a slight change from previous designs and mounting the gearbox inside the boat.  I will need to allow for leg length adjustment, so these panels have slots for the crank arm axle.  I will extend it all of the way to the front edge once the rest is put together.  However, having big slot in the boat means it will take on a lot of water if it is to capsize, so I have added a partitions to seal this area (except for the gap around the shaft and bushing) and to add some strength.

I used the same stitch and glue steps for the footwell panels.  I started in the middle where there is no curve and waited for it to cure.  I need to create a lot of leverage to bend the strips into place, so I wanted a portion of the length to be secure.  I used some clamps to provide the leverage in one area.  Once the clamps created the bend, I tightened the stitches to hold the gap closed.  For the transition to the seat bottom, I cut some scrap wood into bending forms and prebent the panels before attempting to stitch.

I added 2" tape to the inside seams.  On the outside internal corners (such as between the footwell and gearbox housing) I used the System Three gel epoxy to make a small fillet.  I thought I would avoid visible filler there, and the gel is supposed to waterproof and structural for this type of application.

Total time up to this point (not including gearbox): 56 hours