A Case for Displacement Power Catamarans � Pedigree Catamarans

Displacement power catamaran designs in ' Sailboats ' started by StumbleJun 18, Log in or Sign up. Boat Design Net. Power-speed graph displacement catamaran Discussion in ' Sailboats ' started by StumbleJun 18, On another forum I am discussing the realities of electric only catamarans.

One of the bigger issues is the guy I am debating is certain that regardless of the speed, to double speed you need 8 times the power. Which I can accept this at some speeds, I doubt it is a truism across all speeds and all boats. StumbleJun 18, Have a look. Mono hull displacement ship.

Ad HocJun 18, Ad Hoc, That was pretty much my point. The hull in question appears to be a pretty narrow hull planning catamaran. His contention, and what I objected to. Is that if the range is 85nm at 6kn, then the range at 3kn would be infinite power recovered by 3. He displacement power catamaran designs basing this on the fact that his kayak at 5. Do not know why, but I can be Catamaran Manufacturers Turkey wrong, my curve is incorrect.

The curve is for another boat type but, why is incorrect?. Hopefully, Ad Hoc, a reasoned explanation for what seems to me totally out of tune. Ad Hoc, you may be right, it is possible that I should not give advice Plywood Catamaran Sailboat Plans Open to anyone, but I'd like you to tell me why displacement power catamaran designs is wrong curve.

Maybe you can say that it is not appropriate to the case discussed in this thread, but still do not know how can you displacement power catamaran designs that this is an incorrect curve. Would you be so kind as to displacement power catamaran designs it to me?.

I do not pretend to know everything, and when I'm wrong, I really appreciate you showing my mistake. Thanks, my friend.

Tansl, Please read my post 3. If this does not make sense, then it is QED I am afraid, and in which case you need to take a major refresher in hydrodynamics. Okay, I "need to take a major refresher in hydrodynamics", but why " graph by Tanls, is a good example of incorrect data "?. I can not understand.

How can you know the data and know that they are incorrect: I can not understand. Really, it is a question of hydrodynamics?

Obviously if doubling the speed is going to require 8 times the power and fuelit is not the right hull-form for the job. There are plenty of planing hulls where increasing speed through sections of the speed band actually improves mpg, which simply could not occur if the formula quoted applied. Mr EfficiencyJun 18, Displacement power catamaran designs about displacement hulls : the power required at each speed depends on several factors, some of them are a function of the velocity squared.

So that would be the only relationship, not direct, that could be set. Saying that double speed means 8 times more power is not correct. It would not be correct for Lorem lpsum 307 boatplans/builders/asia-harbor-yacht-builders-501 asia harbor yacht builders 501 displacement cat, displacement power catamaran designs you went out of your way to design it that way!

Not sure why this thread is in the monohull sailboat section It is unlikely that any boat is equally efficient at say 8 knots and 16 knots. I'm not going to give graphs or equations, but just some displacement power catamaran designs Lorem lpsum 307 boatplans/sailing-boat/sailing-zatara-boat-size-formula http://myboat307 boatplans/sailing-boat/sailing-zatara-boat-size-formula.html - ie actual facts not theory.

I have motored a 35ft cruising sailing catamaran at 8 knots with twin 9. Richard WoodsJun 18, For small planing boats, being more efficient at 16 knots than 8 knots would be normal, but presumably the Displacement power catamaran designs is only interested in displacement cats in this discussion. Agreed, but a non planing cat might well do 8 knots Lorem lpsum 307 boatplans/jon-boat/diy-jon-boat-camo-kit http://myboat307 boatplans/jon-boat/diy-jon-boat-camo-kit.html 16, as I illustrated.

Those are more likely speeds than 4 and 8 knots. Of course it isn't just hull shape that is optimised for a certain speed range. It is unlikely that a propellor, unless it has controllable pitch, will be efficient over the speed range either Richard Woods.

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This can mean that speeds must be reduced to such a degree that planing is no longer possible. In the case of monohulls, these two forms generally exhibit very different performance characteristics in terms of speed, whereas in catamarans they can be very similar. If higher speed is desired, then planing hulls become the better choice. A Case for Displacement Power Catamarans. Unfortunately, this hull would be laterally very unstable due to its slim profile and have very little internal space making it impractical for most applications.
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