Ivo’s F1 Build

Two days in the wood stacks and found barely acceptable wood. Then Day 1 Prep.

I spent two days in every lumber yard in the area and was able to find barely acceptable wood.  My shop is too small to process the wood as I would have liked, with my bandsaw and planer, so I set up some horses and used a portable circular saw and my Stanley jointer plane on the long pieces.  Once i got a straight square edge on the gunwales and stringers i used the thickness planer.  The shorter pieces will be processed on the band saw.  Progress after prep day 1 (6Oct2019); gunwales, jigs and forms. Part of the day was spent finding wood:

Making do

Parts, jigs and forms done after day 1 and material that is not to be part of the kayak.

I also marked the tenons on the gunwales.  ‘love the smell of cedar.


Prep Day 2

Wow that was fast. I now have all the wood cut to dimension.  The foredeck beams are drying.  I still need to bring a few pieces down from 3/4 to 11/16 inch.  And somewhere in the build, I think I will need to shape the stems.  I also need to make the special sticks.,  I have only gotten through the prep video, so I have no clue where those sticks fit, but I’ll get there.  It got too dark to keep working outside.  Also too dark for photos.  Have to wait until Saturday for the photos.  If I have time after work on Thursday, I’ll mortise the gunwales.  I am thinking of making a third jig for the first foredeck beam.  It does not look like it will quite be square to the gunwales, but won’t be at the flat beam angle either.  That could hold up the beam mortising if I make that extra jig.  (Did I mention that I am a bit of a perfectionist).

The prep video with the plans covered everything I needed to get the parts made.  This is a lot faster and more straight forward than I ever expected.

Building up the nerve to bend the coaming.  I am contemplating using ammonia for the bend.  It is supposed to make the wood more flexible than steam without any loss of strength once the ammonia evaporates away.  I have two coamings cut so I may experiment.  Also need to find ring nails, but don’t want to order the accessory kit until I find out if I can bend the coaming or if I will need a finished coaming.

In the meantime, it is time to start watching the build videos.


Photos from Day 2 and Ammonia Bending Experiment.

This weekend I had light to photo graph the second prep days work.  This completed all of the wood cutting and dimensioning.

All wood cut and dimensioned by prep day 2

I picked up the pieces and it struck me how little wood actually goes into a kayak.  Guess that’s why they are light.


Coaming Tapering Jig

I cut a 3/8 : 13 taper in some scrap wood and used it to taper the ends of the coaming.

The coaming and coaming taper jig

The jig worked very well.  I also made a 1/2″:13″ taper for the lip.  It also worked well.

I filled an 8 foot section of 1.5 inch OD PVC pipe and soaked the coaming in it for 90 minutes.  I then attempted to bend it.  When I looked at the broken ends of the coaming, I could see that the ammonia solution had only penetrated 1/16 inch.  The failure initiated in the dry wood rather than in the outer fibers.  The taper jig worked equally well on the second coaming, which is soaking overnight.  I’ll keep you posted on how that goes.  I am making a 5 degree jig for the first deck beam.  I need to get some longer 4mm x 1mm screws to attach the jig to my router.  I should order the accessory kit, but I want to see whether I need to buy the completed coaming.

I do not believe that bronze is compatible with ammonia and 304 stainless steel, which is compatible with ammonia, is not really compatible with salt water, so I wouldn’t use ammonia on an ocean going kayak.


More Ammonia Testing

I soaked a new coaming for 24 hours in 10% ammonia.  It broke.  Up to point where the thickness got to 1/4 ìnch it bent around the 7 inch diameter.  Looking at the break, the 10% ammonia solution soaked in about 1/8 inch from either face, leaving 1/8 inch in the center.  I solved the differential equations for diffusion into a flat media and found that the time it takes to soak in is proportional to the thickness squared.  This test and the previous test both conclude that 54 hours will be required to completely soak into a 3/8 inch thick piece of kiln dried white oak (diffusing across the grain).  That means it will take 96 hours for a 1/2 inch (probably less since it will also be difusing with the grain).  Also the 1-1/4″ coaming swelled against the inside of an 1-1/2″ PVC pipe.  I’ll need to use 2″ PVC pipe.

I bent the broken piece “backwards” with the thin end around the 7″ diameter.  Worked great and almost no spring back.  The coaming is as strong and stiff as the untreated oak.  A 2″ diameter pipe and cutting a new coaming and I will give ammonia another shot.  (I have the experience with steaming, but I want to experiment with ammonia.

BUILD DAY 1/2 27Oct2019

Could only work on the boat for a half a day.  I started the actual build today.  Kerfed the ends, bound them and pegged them.  That was easy.  These tenons have no square surface; how is this going to work?  Brian’s marking and cutting method is absolutely brilliant.  What looks like a daunting task took about an hour.  I had made an extra 5 degree routing jig for the first deck beam and it was spot on.  Did not have to wallow out any mortices.  Had a nice long look at the deck before I had to put it away.  The taut entry curve, the sweeping rise in the gunwales, rounded but trim aft curve; this would pass for a work of art.  Still have the straps on, since I had not purchased 1/8 inch dowel.  The 1/4″ dowel prep was done almost before it started.  I would never have thought to do it that way.  I need to get busy and order the backstrap and foot pegs.  The coaming rim is soaking in 10% ammonia and is going to soak for 54 hours before I try the bend again.  Off to a birthday celebration (Shh, it’s a surprise.)  No photos, the garage is a mess, but I’ll add some next weekend, when I can get it outside.


A 54 hour soak in 10% ammonia worked for 3/8″ thick coaming.  The other thing about bending with ammonia is that you have to bend achingly slowly and let the wood flow into shape.  I clamped the center and held the leather strap while I bent and compressed coaming to get an even curve.  It took about a minute to bend the small radius and get the coaming and strap behind the short pegs.  After that it was just go slowly and steadily around the rest of the form.  I used three spring clamps per side and just let the wood “flow” to the next peg and then attach a spring clamp.  The inner end stopped at a peg, which was convenient.  I used a small scrap to clamp the outer tail flat against coaming.  It is drying now.  I ordered the backstrap, foot rests, straps and ring nails from Brian.  Can’t find a good set of float bags that are in stock.  I am considering making the float bags myself.  There is some intriguing U-Maxi Clamp closure material from Illinois Tool Works that would be perfect, if I can find a place to buy it.  The TPU coated nylon is readily available.

The ribs need to be steam bent so that they will stiffen up fairly quickly after they are bent.  I don’t think ammonia will be appropriate, but I will try with one of them just to see what happens.  I also have a bending iron that I use for guitar side that I might try as well.

Had some daylight to photograph the assembled deck.

F1 assembled Deck

1Nov2019 I CAN’T COUNT TO 20!

I measured the ribs tonight and ended on the back at rib 19 not twenty.  I missed the “30” on the plans and put the first (2nd really) mortice @ 36 inches.  Everything was right, but I hadn’t made the first set of mortices.  Wasted about twenty minutes getting the router out, seting up, cutting two mortices and putting it back away.  I did remember to re-measure the ribs.  Ready for cutting ribs.

Broke the coaming lip when I tried to bend it, but was able to bend the broken half by taking the coaming off of the jig, clamping the front center and applying spring clamps side by side until the tight bend was made.  This kept the backing strap firmly anchored to the lip and had the lip supported every inch around the tight bend.  Had a second coaming ready for tapering.  14% strain in wood is going to require splitting the outer fibers or crushing the inner fibers.  I have been unable to hand hold the backing strap tight enough to keep the outer fibers from splitting without using spring clamps right next to each other.


I had spare shelving material 1 foot by 3 foot.  High density compressed wood flour, covered with a plastic veneer; no sense in buying something else.  I used this when I made the steambox; what could go wrong?  The veneer (really just film) let the steam through and the box fell apart within 12 ribs.  I’ll be making a new steam box.  The kiln dried bending stock had more severe run out and twisted grain than I originally thought.  Every rib that I thought was iffy, failed.  I got 8 ribs bent out of 12.  I had soaked ribs 1 through 3 in hopes of getting the heat through moist wood better than dry.  Ribs 1 and two cracked at a runout area. Rib 3 worked, but was swollen so that it would not fit the mortice.  I clamped it flat aginst the inside of the gunwales until it dried.  I was then able to put it in the mortices.  I found that I could remediate some of the poor bending with a heat gun using a cam strap and wood piece under the gunwales to hold the shape while I remediated the curve.

Another way to thin the ends to 1/4 inch:

Thinning rib ends

I used a band saw with minimal blade exposure to thin the ends.  Put a stop on the back to maintain the depth.  Worked like a charm.

Now to build back up the optimism to finish bending the ribs.


With the help of my son, I bent the coaming rim.  It has been soaking 4 days.  I clamped the backing leather tight.  I took the coaming off of the form and clamped the middle of the rim to the front of the coaming.  I slowly bent the rim (really let it creep under the weights of the clamps holding the backing strap) slowly.  When enough of it touched the coaming, Kevin added a spring clamp directly next to the last clamp.  Once we worked our way to the straighter section we clamped it and removed the clamps around the tight section.  I put the coaming with rim back on the form.  I clamped the center front and about 45 degrees to either side.  I then used four spring clamps per side and worked around the pegs.  First the inside tail then the outside tail.  Work very slowly when bending with ammonia.  It is on the form drying now.

I rebuilt the steam box with exterior plywood.  I used contact cement to glue aluminum foil to the inside of the plywood.  This should last.  Maybe I will find time this weekend to finish the ribs.

Saturday 9NOV2019

Found a small piece of oak that was air dried and long enough for ribs 1 and 2.  It was rift cut, but really straight grain.  I split it, planed it and used that surface to cut parallel to the grain.  They bent just as easily and pretty as Brian’s videos.  I split and planed the piece of kiln dried oak that I had been using.  The pieces ended up flat cut, but with very little runout.  It bent suitably, but not like the air dried.  All ribs are bent and in.  The keel height is set.  It is looking a lot like a kayak.  Monkeying around tweaking the rib shape to get the fit up to the keel as good as possible.  I did clamp blocks of wood along the gunwales spanning the mortices so that the mortices wouldn’t split.  Probably unnecessary, but i really didn’t want to hear that wood cracking sound.  I think rift cut air dried wood is the way to go for future ribs and coamings.

Sunday 10NOV2019 It’s a Hull!

Lashed the keel and stringers on today.  Lashed on bow and stern stems.  It looks like a kayak.  With luck I can peg the auxiliary stringers after work this week and it will be on to Day 3 in the videos.  I need to get busy, and order the skin and coating from skin boats.  I also need to find out about skinning in cooler weather.  Again it was too dark (and cold) for photos.  I’ll see about posting a photo if there is a day this week where I am home before dark.

I did deviate from the order of things.  I clamped the stringers on (in postion) without the rolling taper and placed a 5/8″ thick block against the stems to mark the end of the stringer to get the correct angle.  I also placed it above (but the kayak was upside down) to mark the end of the initial taper.  I made the initial taper 3/8″ shorter to account for the increase in angle as it get bent in the extra 5/8″.  I cut that bevel with a saw and the planed to the line.  From there I rolled the taper out to 32″.  Got a good fit of the stringers to the stem.

This is really a rewarding way to build a kayak.

I think I have a source for green if not air dried white oak.  It will be cut to 8/4ths  I will definitely split it and plane a parallel surface so that there is no runout.  Then I will sticker it and dry it down to 25%.

Ivo Garza

View posts by Ivo Garza
I am an engineer, but I am the son of a cabinet maker and have worked wood since I was 2 (yeah, but they didn't let me do anything but sand.)

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