Low horsepower proa or motor canoe hull shape?

Probably depends on the type of fishing, trolling for game fish is not in the least affected, but anchored in shallow water it could be a problem, though alloy boats are noisy in any configuration.

 

my flat bottom pounds slaps sneezes and gurgles and I have been surrounded by snapper and cobia while chum fishing, I don't think most fish care.

 

Cobia approach boats fearlessly, I recall a trip where we caught two 80-pounders.....and there were much bigger ones milling around the boat, could have been 150 pounds by appearances, world-record class, easily. Most fish in the larger sizes are shy of boats. Wahoo also appear unperturbed by boats.

 

Where I fish the snapper can be very shy in the shallows (<10m deep). I tend to catch more fish per rod in my plastic kayak than in my alloy boat. Even in the kayak, a couple of times I haven't iki spiked a snapper properly during a hot run of fish and the noise it made flapping around in the catch bin ended the action instantly.

 

Here is a quick drag estimate for a 500Kg 5.5 m square stern cargo canoe. 4.25m/s=8.26knots. 300N * 4.26m/s = 1278 watts. That's assuming 100% thrust efficiency. I don't know what typical outboards' efficiency is.

 

Johnhazel, thank you so much. That is great information. I now feel confident to go with a skinny planning hull. About 4.5m waterline length and 1 m beam. Construction will be tortured plywood with panels composed entirely of straight cuts with the exception of the forefoot. It should take exactly 4 sheets of ply with almost no wastage. Not sure if i will use 4 or 6 mm ply. I know it will work with 4 but 6 would be nice if the forefoot bends will allow. Here is a model.

I can spread the sides out by eye to create more flare in the topsides and lessen the v midships but you get the idea. Thanks again for crunching the numbers!

 

4mm for planing hull is very little. Also building from 6mm will be much nicer than the very floppy 4mm.
A boat build to consider is tweak (upscale and desing evolution from Ross Lillistone's fleet)

I think the person who built it used a lot of longitudal strips (my english fails me today) for extra rigidity.

The thread is a good read with builder's notes.

Tweak / Fleet build in Lithuania [2016] http://forum.woodenboat.com/showthread.php?213187-Tweak-Fleet-build-in-Lithuania-2016

 

Cheers, I saw that one on woodenboat forum. Thanks for the advice on plywood thickness. I am not concerned with the adequacy of my scantlings. I've built enough boats to know what I can get away with. I like the fleet/flint designs but the freeboard is too low for my tastes. And I prefer to build by eye than to an exact plan. Thanks very much for the suggestions.
Your English is excellent, by the way.

 

That hull is going to be veeeery tender if you want to walk in the boat past the halfway mark. Tying the bow rope to a jetty will be a real no-no. Also, if you have any kind of load in the front, when you get out, it will be a problem.

If that model of yours floats, get some scaled weights and test the reactions.

 

Thanks rwatson. I would flare the midsection and somewhat flatten the v midships in real life. Good point about tying her bow up. On the one hand all weight will be centered when one leans toward the bow, but you are right. I see this design more as an 8 foot punt with a 7 foot fairing on the front. The model does float, that's why its made of plastic rather than paper. I will definitely experiment with weights as per your excellent suggestion. Is it just a matter of scaling my weight down same as the model is scaled downbin size or am I missing something crucial (besides the model not having correct scale weight)?

 

Hi interesting post, love the wooden boat festival in tasse by the way, a must for those who have never been. I think it's a common quest to have an efficient small capable craft these days and there are many ways to achieve your desired outcome. I toyed with the long skinny monohull solution but dismissed it in the smaller sizes due to its limited functionality in my desired role. It was difficult to undertake most of the typical activities I enjoy whilst on the water in this style of vessel for me. Basically the lack of stability was the main problem closely followed by a bone jarring and wet ride and thirdly the lack of sea keeping ability afforded by a self draining deck. I spent considerable years attempting to cure my dinghyitis as the Admiral calls it and I think I have found a reasonably successful cure. My dinghy has considerably narrower hulls compared to your average small powercat and the hulls are more of a semi displacement design closer to a small sailing cat than a powercat. In a two foot chop there is zero pounding, it does not pound at all, ever!!! You have as much chance of getting a hobie 16 sailing cat to pound, absolutely zero!!! It is self draining and unsinkable with it's foam core construction and very very dry for an open vessel of this size. And as for stability, you speak of the possibility of difficulties walking forward in your proposed vessel, you can literally waltz around in mine, you can stand on the gunwhales in fact two people can on one side and not capsize and it weighs 45 kilos and is semi amphibious with the wheels. It's not for everyone and there is no one boat that is, otherwise we would all have one and the great quest would be over, a cure for the disease that ails us all, a panacea, or perhaps panasea, if you will. My admirals uncle lives at the wooden boat school in Franklin with his dog bosun on his yacht. He teaches wooden boat building there although currently his health is not the best to say the least. He has built many small craft of varied design. Mainly small rowing and sailing craft, which by necessity, must be easily driven. At lower speeds a beamier hull may be afforded however as speed increases the beam must be reduced to maintain efficiency and this in turn robs you to some degree of form stability. The only possible solution I could discover was multiple hulls to keep the more efficient narrow hull form yet maintain stability. This could be in many forms however I felt for my needs a cat was the best. I can put a queen size matress on the deck and still walk around it in a 3.5 metre dinghy. Thats functionality that my Admiral demands or I'll be just another landlubber seeing out my days in a rocking chair in a house, for me a fate worse than death. I have lived on my boat for fourteen years and travelled thousands of miles, a good dinghy is a necessity and i think thats what my magic carpet 3.5 is for my needs anyway. After nine years of dinghyitis I think I may have a cure. Good luck with your quest and i hope you succeed.

 

Sure, your boat weight isnt to scale, but the bouyancy tests would be pretty relevant.

For scaling weight , check out scaling weight http://forum.woodenboat.com/showthread.php?49716-scaling-weight

" In general if you scale a 3D object to 1/N its original size, its weight will be 1/(N*N*N) times the original weight.
So for a 1/4 scale model your weight will be 1/(4*4*4) = 1/64 th the original weight."

Using civilised weight, if you boat scale is 1:10. Then a heavy skipper ( say 130 kilos) wouldnt be 13 kilos on you model, but 130 / (10 x 10 x 10), or .13 kilos ( 130 grams).