Hull design

Gary F

Gary F

Member
Could someone please explain the difference and purpose of some hull designs. For example Displacement versus planing hull. Which is best used where. And show some examples if possible.
What do you prefer and for what reasons?
 
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Displacement only goes as fast as the displacement speed of the hull, most hulls make about 6-10 kts, no matter how much HP you apply. The can handle rough seas well, but also usually draw more water.
Planing hulls jump up on plane, are faster and normally shallower draft. Vs. a displacement hull of similar dimensions, handle seas less well. Other with more experience than I can explain why.

Need a fast boat to go a long distance? Planing hull.
Rougher water with no need for speed, Displacement.
Most of us probably need a hybrid between the two.

There are those with more sneakbox experience than I who can provide more comments on specific hulls.
 
Displacement Hulls are often used in larger boats because they tend to be much more fuel efficient.

Miller
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Yes, like ships. The increased hull length allows increased hull speed and a ship can produce a hull speed many times a small boat.
 
If we're talking about sneakboxes there are so many variances to sneakbox hulls and many that do not fall perfectly into one category or the other. If you want a comparison of two or more hulls you might get a more specific answer.

Net:Net a displacement hull will handle rougher waters at slower speeds than a comparable planing hull. How much water they draw doesn't necessarily hold true. My semi-displacement hull can run in shallower water than my father's planing hull due to my hull floating higher.
 
If we're talking about sneakboxes there are so many variances to sneakbox hulls and many that do not fall perfectly into one category or the other. If you want a comparison of two or more hulls you might get a more specific answer.

Net:Net a displacement hull will handle rougher waters at slower speeds than a comparable planing hull. How much water they draw doesn't necessarily hold true. My semi-displacement hull can run in shallower water than my father's planing hull due to my hull floating higher.
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And just to confuse things more the displacement/semi-displacement hulls are sometimes run with enough hp to make them jump up over hull speed and plane (even if not as efficiently as a true planning hull). It can for sure be done - maybe not in a classic fully rockered spoon shaped hull, but there are some rockered sneakboxes that are displacement hulls that are run at 10-15 knots and that far exceeds the hull speed (which is 4 or 5 knots).
 
I am not a speed demon and need to get from point A to B as quick as possible. I do want to get into the shallows to hunt puddlers though. Suggestions on boat types as far as names go.. Blackjack, Huff, Widgeon
I am thinking all fiberglass now that someone mentioned you should keep wooden boats garaged.
 
Once again, I am no expert, but a glass-over-wood boat with a proper cover should be fine outside. So don't let that limit your choice.
Is in a garage optimal? Yeah, for any boat that is the best choice.
But with a good ventilated cover that keeps water from ponding in the hull and allows it to breath, any properly constructed glass-over-wood boat should be fine.
 
I agree with Craig. A lot of variables to the depth of water they will run in. I can run my 12ft Zack Taylor Widgeon (wood & glass) with a 9.9 motor in much shallower water than Steve Steffy's Chuck Huff but he is running a 15hp 4 stroke. Widgeon is displacement and Huff planning, but I'm guessing big difference in motor weight which might account for difference in running skinny water. In open water he leaves me way behind. I can get about 9 mph out of my boat, he is somewhere just below the speed of sound.
 
I am not a speed demon and need to get from point A to B as quick as possible. I do want to get into the shallows to hunt puddlers though. Suggestions on boat types as far as names go.. Blackjack, Huff, Widgeon
I am thinking all fiberglass now that someone mentioned you should keep wooden boats garaged.
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In my opinion, a sheltered boat of any construction will last longer. It does not take much effort to protect your investment. I have a wood/glass Sam Hunt displacement hull. As Tod indicates, I can/do overpower her with a 15hp. I can make 9 knots fully loaded, and close to 14 knots in the summer for a cruise. Mine is 12ftx5ft and was built as a sailboat. It rows well, displaces about 6" empty and about 8" loaded.

With respect to garaging a woodenboat, and not a glass or aluminum... If you don't proected a glass boat from UV, it will crack and chalk. If you let any boat sit with water in it, it will get ugly. Wooden floors in aluminum boats will rot, imperfections in a glass boat will get soft, ice will do damage, etc. Keep the standing water, leaves, and wet soggy stuff out of any boat is easy. True a wooden boat will have more places to rot if not cared for, but a cared for wooden boat is something to be proud of and adds to the hunt in my opinion.
 
I have a Bud Miles BBSB which is a displacement hull. I have never been scared of any water condition whether I hunted my home waters on Kentucky Lake, Barkley Lake, Ohio River, Mississippi River, or Lake Erie around Toledo when I lived up in northern indiana. But I have hunted a lot of aluminum duck boats in the 15 to 20 foot class where I had second thoughts about handling the same waters.

Regards,
Kristan
 
I am not a speed demon and need to get from point A to B as quick as possible. I do want to get into the shallows to hunt puddlers though. Suggestions on boat types as far as names go.. Blackjack, Huff, Widgeon
I am thinking all fiberglass now that someone mentioned you should keep wooden boats garaged.
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My fiberglass over wood Devlin BBIII sits outside all year in Alaska. Frozen solid half the year and then baking in the midnight sun for 15 to 18 hours a day at least three months in the summer. Its fine since it is a fully encapsulated build. As long as the epoxy resin is covered with paint to prevent UV damage and any nicks and bruises from being used are sealed and painted. Keep the drain plug clear so it does not fill up and freeze.

Whomever told you that about wooden boats was probably talking about wood plank boats with exposed wood on the interior. A modern fiberglass over wood boat will not have that issue unless you never maintain it during or after the season. That is were most guys fail and start bad mouthing their boats. Even all fiberglass boats get problems when their floors leak and the foam gets soaked due to bad design, construction, and maintenance.
 
Have I said recently how much I like aluminum?

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I don't know if John Kuhn (in NJ) is still making them but I've been very please with this 1/8" thick hull sneak. She's a "fricken" tank that I've busted and bounced off ice with, that's pretty much in the same weight class as either the fiberglass or wood sneaks. I know I wouldn't want her as my only boat, as a 12' sneak just isn't versatile enough, but that's not a problem as I have a choice of boats to hunt or fish from.

Scott
 
Well now we are talking... Lol I just so happen to work in a metal fabrication shop that does alot of alum. welding. I do not do the welding. I do the cad and 3d modeling in the office as well as program the laser cutting, waterjet cutting and cnc punch machines. We have all grades of alum. here... 6061, 5052, 3003 plus i can get what ever i need for sheet sizes. We laser up to 3/16" alum and water jet 5" thick alum. Did i mention we have a full machine shop as well as 12ft shear and 12ft press brakes for forming as well as rollers...
 
Well now we are talking... Lol I just so happen to work in a metal fabrication shop that does alot of alum. welding. I do not do the welding. I do the cad and 3d modeling in the office as well as program the laser cutting, waterjet cutting and cnc punch machines. We have all grades of alum. here... 6061, 5052, 3003 plus i can get what ever i need for sheet sizes. We laser up to 3/16" alum and water jet 5" thick alum. Did i mention we have a full machine shop as well as 12ft shear and 12ft press brakes for forming as well as rollers...
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could I just send my auto cad boat drawings over and just sit back and wait for the delivery truck.

just kidding.....sort of.
 
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Mike,
If you send the cad drawings i will build the boat and test her out for you for a little bit just to make sure she is worthy...
 
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Well now we are talking... Lol I just so happen to work in a metal fabrication shop that does alot of alum. welding. I do not do the welding. I do the cad and 3d modeling in the office as well as program the laser cutting, waterjet cutting and cnc punch machines. We have all grades of alum. here... 6061, 5052, 3003 plus i can get what ever i need for sheet sizes. We laser up to 3/16" alum and water jet 5" thick alum. Did i mention we have a full machine shop as well as 12ft shear and 12ft press brakes for forming as well as rollers...
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Wow, that would seem to solve the problem right there! Adapt a set of Devlin plans to aluminum, get them into CAD and crank up the cutters. Give your welders a few cases of their favorite adult beverage and you are in business.
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