Keel Shape Reccommendations and Michlet Help

And typical speeds would probably max out from 4-5 knots, though I’d put 6 as an absolute max to be sure

 

Yea we train as much as possible every year starting in early September. The competitions are in March and June. And yea that makes sense about the weight being the primary killer of speed and maneuverability, however there is not much more we can do to reduce our weight. The canoe will likely weigh 200-300 lbs, and it will be designed with the worst loading scenario in mind (4 paddlers: 2 weighing 200lbs and 2 weighing 150). So designing around an expected 1000 pounds is what we have to do. I think I understand what you’re saying about how Godzilla optimizes the shape of the canoe when given a displacement, but my primary issue is actually being able to use Godzilla/michlet. I only have the free version of delftship and it doesn’t allow me to export the model in the required file type for Godzilla/michlet. Also, when I say “fast” or “maneuverable” canoe I mainly just am asking about which shapes would yield the lower amount of resistance for speed/turning.

 

Also there is a bit of a length constraint. It’s about 20 feet give or take. This is due to the fact that the table on which we set the mold and pour the concrete on is only about 20ish feet long.

we could potentially make it shorter, but that sacrifices turning ability, especially during the coed race with 4 paddlers. And turning is probably equally as important as straight line speed. These aren’t like regular canoes that can turn on a dime and get up to speed quickly. The turns in these races are pivotal in determining who will finish quicker, as the canoes lose a TON of momentum and it is extremely strenuous getting the canoe back up to speed when coming out of a turn. Also, during the coed race, the weight is so great that the waterline easily comes up to, or over, 50% the way to the gunwales. In short, they’re VERY hard to turn and get back up to speed

 

If you look around online, you are likely to find Freeship, from which Delftship was derived. Versions up to 2.6 were supported by the developer and had complete integration with Michlet/godzilla. I don't know if your model file could be opened by them or if it would really need to be as you cold expect Michlet to alter the input to match the best results for the desired criteria.

 

20 feet or so length limits makes things interesting, fitting four paddlers in also a challenge.

Michlet/godzilla will output a set of coefficients (typically 7) that describe the underwater hull shape; fwd waterline, midsection, fwd keel line, aft waterline, aft keel line, location of midsection from bow, and location of midsection from stern. The last is often redundant, it's rare to have any parallel body in such a short craft.

You are free to use any method available to arrive at a shape that matches that form. I use some ancient Autocad autolisp routines and match shape, surface area, prismatic coefficient and the like to within less than one percent. Since you have several different displacements to deal with it somewhat makes sense to design around the middle displacement then simple math and knowledge of the waterplane area will let you calculate the extra depth of the heaviest case.

In order of importance to do well (win) in such a competition; motors, mass, then shape of canoe. I've designed canoes for paddlers who would have been competitive in a number three washtub if gave them a little time to reshape it with a couple of sledgehammers. Regarding the turns, canoe racers often help turn their boats by leaning to the outside of the turn. A secondary thought, since you have to reaccelerate from the turns the shape and size of your paddles have some influence, I have a "4wheel drive" bent shaft paddle with a lot of blade area for use on expedition trips when I'm heavily loaded.

Best wishes on the deal, hope you all do well. Let us know how it goes.

 

For me, with lifetime building and sailing
if you cruise as in going foreign of places where you dry out , that is not haul out then finns are out, as sailing boats need consideral support to hold them from pitching over or sinking into mud
so Scheel is the answer, this keel carries ballast low and can most often have a sole so wide wherby the boat can actually sit without support if on level ground

 

You can't spray onto foam?
Or will the concrete have foam in it?
Or both?

 

"That was an old theory from many centuries ago that has been proven wrong."

---
<removed>

He doesn't know the motives and reasons for those old solutions; he believes the world was born yesterday afternoon.

 

These people were people sailing in a real world, and they sailed in harsh conditions.

And now some armchair theorist comes along and tells them: that bow is wrong... it's not optimized for 0.30-0.40 Froude.

It's completely ridiculous how these people pontificate about old solutions to real problems.

 

CarlosK2 you are mistaken.
Gonzo is correct in his statement.
Your comments and attitude are malicious and uncalled for.
Please remove your ridiculous posts and stop with such outlandish nonsense.
Thank you.

 

Those who went out to sea to work wanted to return alive.

Their interest was neither the interest of a rowboat with very little propulsion force nor the interest of a racing sailboat.

Year 1825, port tavern

- Guys, we're wrong. I heard a guy in the year 2025 say that the ultimate criterion isn't returning to port alive, but rather a few tenths of a knot around Froude 0.30

- Haha

 

On the other hand, we must distinguish between old solutions and the explanations and reasons that were given.

Whether the reasons or explanations were wrong is irrelevant to solutions that worked

Today we see yachts designed by guys who think they know a lot (about irrelevant details) and who, by forgetting the important issues, design yachts that behave insufferably when the wind blows Force 7.

 

Modern bow shapes and underwater sections on "some" North Sea offshore support vessels are closer to 15th Century bluff bowed sailing tubs than some would care to admit.
His comment was not malicious, do not try to make it appear so. Please, dont make this place like the WBF, his post is in no way deserving of your response to it. IMHO.

 

The response is deserved in the context of his usual posts. He hijacks threads with his surfboard nonsense and other non-related things. As far as any North Sea offshore support vessel, that is as far removed from a canoe as a vessel can be. Please stay on topic.

 

He was responding to your "bow shape proven wrong" theory. You made it part of the topic.
Attacking people for what you believe is "nonsense", is not staying on topic either.
It would be nice if everyone stayed on topic that is boat design, not personality conflicts.