small shanty boat cat build log

hi,

my project is at a state where there is finally something worthy to see, so I'm starting this build log for anyone who may be interested

This is a small shanty boat on a cat hull. The base design is glen l huck finn (16' version) Huck Finn https://www.glen-l.com/12-28-Huck-Finn-trailerable-pontoons/products/169/ . I'm making the pontoons 10% larger to get a bit more bouiancy and build a bigger cabin .

This boat will be used on protected waters, lagoons and rivers. Propulsion will be electric, will have a big flat solar roof and I expect to have unlimited range on clear summer days (ie get all the power for the engine straight from solar). The idea is to have a big camper-like cabin, with beds for 4-5 people, kitchen and everything for a comfortable multi-day cruise. From where I live there is a network of old waterways that where part of venice domain, mostly unused today but I should be able to get to venice in a week or so (130km~) .

So the boat will be kinda short and small to navigate tight and/or shallow channels and lagoons, and to be trailerable from my home (~40km from water, and also the closest launch ramp is kinda terrible and very small - at least is free...).


btw, skin from okume exterior grade plywood, frames from spruce (thats what I find at the store here). Glue with titebond3 and epoxy.

 

here we have stringers and bulkhead elements, now I am starting to assemble the hulls.

I will make one hull at a time to recycle a single strongback, and also because I have little inside space (outside it is ~5C, a little cold for the glue).

I'm using mostly titebond, but I have to do epoxy where I need more gap filling or critical joints under the waterline... so far I don't like much working with epoxy, a lot of work to prepare and also slower to cure, titebond is ready to use ad quicker to set, I think I'll use epoxy only for those joints where titebond is not recommended.

 

mounting chine logs

had one explode... well I was bending too close to a joint, and clearly with not enough steam/heat >_<
made quite a big bang! noise
replaced the broken section, the new one bent ok


I had to wet the wood for bending, and I know that epoxy does not like wet... how much time do I have to wait before epoxing? (I did not totally soak the piece, but it took some water to bend)
I know there are many variables, I need just a rough estimate... it is a few days or a couple weeks enough, or I am looking at months? assume room temperature with decent airflow and low humidity (I'll keep the dehumidificator running in auto mode)

 

Your best bet is to buy a moisture meter.

 

I think I actually have one of those

for firewood XD

but with that you were supposed to split the wood to accurately check the moisture inside XD, I don't think I want to do that XD XD

 

You need to split the firewood because it was evenly saturated at the start and will have a dry surface but a wet interior. You started with dry wood and wetted the surface. Also, it is much thinner than firewood usually is.

 

You don’t need a meter.

Just run a fan on it for 3 days or so. Check it for a cold to the touch feeling and if feels cold keep adding a day until it doesn’t.

You are not adding cellular water, but free water that fills intercellular spaces. A moisture meter can be used, but not needed.

In the future, if you are using epoxy; you ought to consider laminating anything difficult to bend. You rip it down thin enough, place the wood in situ or in location, then pre wet both sides and then after 15-30 minutes bond it with about 2:1 cabosil to epoxy and clamp enough for a one millimeter bondline. Continue until thick enough, clean squeezeout. Next day, you can continue working.

 

I've had one explode on me too. Sobering. On a bulkhead.

Moisture meters are great, especially if you already have one.
Did you find it?


In case anyone else was wondering:
In text, XD (or xD, xDD) is an emoticon representing a laughing face with squinted/closed eyes (the 'X') and a wide-open, grinning mouth (the 'D'), used to show strong amusement, laughter, or silliness, similar to "LOL," often with a nostalgic or slightly ironic tone

 

thanks for the suggestions!
I did follow the plan instructions, which called for single piece bent chine log, and laminated sheer clamp. Sheer clamp bent without breaking, so that's good.
On the second frame I might try laminating the chine log too...

meanwhile the first frame is complete, and I'm moving on to planking ( is planking the right term? since I'm actually using plywood and not planks )

should I wet the plywood for bending?

I'm mostly using 8mm plywood... I am a little concerned about bottom stiffness for trailer loading, my trailer has rollers and I worry that too much concentrated pressure on the bottom may damage the lighter plywood... should I use an heavyer ply on the bottom?

My local store has only 4mm-8mm-18mm -_- 18mm is really too much, I would have liked 10-12... I could laminate 8mm+4mm, even if it would cost more than the 18mm... >_<


btw the bending of the bottom elements (chine log and keel) tends to pull the stem upwards, the sheers stay flat only as long as they are secured to the strongback. I guess that is normal, once I add the plywood sides those should hold it in shape I think.

 

Great progress Aleph!

All of your questions can be answered with: follow the plan.

Is the ply an honest 8mm or is it good-one-side and actually more like 7mm?
I'd be surprised if it calls for wetting the plywood.

 

Eh, more the second one I guess XD (5 layer btw).

About the fasteners, the plans calls for bronze screws/nails, to be left in place. I am using stainless 316, I know it is not the best but it is what I could source locally... but reading more I understand that, using epoxy glue, I could have used any steel wood screw as temporary fastener, and just removed it after glueing and seal the holes with more epoxy.

Why do you think plans calls for expensive fasteners to leave in place, instead of cheaper fastener to be removed later?


Next question, about trailer rollers...

currently my trailer has this kind of rollers Rullo centrale doppio rinforzato con staffe https://www.osculati.com/it/11026-02.040.72/rullo-centrale-doppio-rinforzato-con-staffe

the plans call for a long skeg element to be mounted in the center of the hulls
should I keep this style of rollers, and adjust the position of the rollers so that only the skeg sits on the rollers (and hold all the weight of the boat)
or should I switch to regolar "round" rollers, and have the flat parts of the hull bottom sit on the rollers?
maybe bunks would have been better for weight distribution, but my local boat ramp is oh-so-very bad, impossible to launch with a bunk trailer from there


last question: plans call for a cap piece above the stem
here I can source spruce, or pine, or beech if I want something harder... is spruce ok (with maybe more fiberglass on top) or do i want something else?
should I maybe reinforce the stem and/or the skeg with a stripe of steel? in this case, the steel is to be mounted above or below the fiberglass?

thank you all for the tips!

 

hi everyone,

new year, making some progress, planking completed and fiberglassing in progress.
I have increased a little the width of the skeg so it can properly support the weight of the boat when loaded on the trailer.