I’m about to start a shanty boat build. Plan is to only ever use at displacement speed. However, have the option to build true displacement(both transoms out of the water) or planing hull.
I notice Jacques has at least on design(GT23) that is a planing hull, but he recommends displacement speed usage. Why would that be?
That causes me to wonder, should I build a planing hull even though I plan to use at only displacement speeds? I suppose at least then I would theoretically always have the option of a bigger motor and planning speed where the inverse would never be true. But what else would be an advantage?
Thanks.
Jbo
Planing boat at displacement speed
Re: Planing boat at displacement speed
A displacement hull will work better at displacement speeds but will not get on plane properly or at all even with a very large engine.
In some cases, the program of the boat must included displacement and planing speeds. In that case, the hull shape is either semi-displacement or planing.
A planing hull will work at displacement speeds but will not be efficient and not as seaworthy.
In some cases, the program of the boat must included displacement and planing speeds. In that case, the hull shape is either semi-displacement or planing.
A planing hull will work at displacement speeds but will not be efficient and not as seaworthy.
Jacques Mertens - Designer
http://boatbuildercentral.com
http://boatbuildercentral.com
Re: Planing boat at displacement speed
jbo that was Jacques response to some one who wanted both displacement and semi- planing spedd in the mid-upper teens.
Tom
Tom
Restored Mirror Dinghy, Bought OD18 built by CL, Westlawn School of Yacht Design courses. LT US Navy 1970-1978
Re: Planing boat at displacement speed
I think this comment from the GT27 study plan is what brought up this question. I had thought the comment was a little more direct, but maybe not.
“ However, this is not a speed boat and she will be much happier at a tranquil pace of 8 to 10 mph with a 25 HP.”
So my question became, why recommend displacement speed for a planing hull.
Since I’m building a boat for displacement speed, my plan is a displacement hull. But never having owned a displacement cruiser(outside a canoe), I have some worry that I will find the slow speed cumbersome in practice. In that case, would be handy to build for planing in the event the slow life is really just too slow. .
Jbo
“ However, this is not a speed boat and she will be much happier at a tranquil pace of 8 to 10 mph with a 25 HP.”
So my question became, why recommend displacement speed for a planing hull.
Since I’m building a boat for displacement speed, my plan is a displacement hull. But never having owned a displacement cruiser(outside a canoe), I have some worry that I will find the slow speed cumbersome in practice. In that case, would be handy to build for planing in the event the slow life is really just too slow. .
Jbo
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Re: Planing boat at displacement speed
I feel you are wise for thinking about it now. You may or may not ever use plaining speed but it would be nice to have the option.
Re: Planing boat at displacement speed
Exactly my point, Fuzz. As it is, I have a fishing boat that I use 95%(or more) of the time below the hump. My wife and I just aren’t go-fast people. . . . But it’s there if I want it.
Program for the boat is 90-10 lake and river use transitioning to probably 70-30 when I retire. So overcoming current could occasionally be needed. But that can be planned for - like planning a takeout downstream, going upstream on the first leg of the trip rather than down, etc.
Probably won’t build to this scale again, so don’t want to set myself up with a boat that doesn’t work for me.
All that said, I am 98% confident in my choice for displacement.
Jbo
Program for the boat is 90-10 lake and river use transitioning to probably 70-30 when I retire. So overcoming current could occasionally be needed. But that can be planned for - like planning a takeout downstream, going upstream on the first leg of the trip rather than down, etc.
Probably won’t build to this scale again, so don’t want to set myself up with a boat that doesn’t work for me.
All that said, I am 98% confident in my choice for displacement.
Jbo
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