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Hull Taper

S

Seven3

Well-known member
Just curious about the science behind figuring what taper to bend the sheets of a riveted hull at (stern to bow taper). You look at some of the old Thurmans and they have a lot of taper making the bow deeper. But the later Thurmans, and the newer Benny Webb’s have less taper. The Don Davis’ and Wardaddy’s seem to have a lot less taper. Is it all just about getting the boat to jump up on plane quicker?
 
Yes, I build mine with 5" of taper per side they tend to be on plane with a throttle blip, wider is better.
 
The older thurman hulls had heavy taper to drop the nose farther, those boats were built specifically to have a proper sized drawer on each side to haul a certain size package(s) that were extracted from certain areas back in the good ole boy days, wink wink.
 
John Fenner said:
The older thurman hulls had heavy taper to drop the nose farther, those boats were built specifically to have a proper sized drawer on each side to haul a certain size package(s) that were extracted from certain areas back in the good ole boy days, wink wink.
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:lol: :lol: :lol: :lol: This guy.
 
Diggin you have a set of those boxes in yours...better make sure there’s no residue left in them LOL. My new one has a set as well.
 

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Seven3 said:
Diggin you have a set of those boxes in yours...better make sure there’s no residue left in them LOL. My new one has a set as well.
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If there's any residue in there, I'll have to blame the previous owner. 8) :lol: :lol:
 
John Fenner said:
Yes, I build mine with 5" of taper per side they tend to be on plane with a throttle blip, wider is better.
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Could you explain further, I'm not understanding what your talking about?

Thanks, Gary
 
When I have the sides bent, say for a 6'8" x 12' the rear will be bent at 8" the front will be at 13",that puts a 5" taper into the hull per side.
 
John Fenner said:
When I have the sides bent, say for a 6'8" x 12' the rear will be bent at 8" the front will be at 13",that puts a 5" taper into the hull per side.
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Gotcha, Thanks, so it's like a slope from bow to stern? Not to go-jack sevens thread, how do you determine the kick up from the side to be bottom of boat?
 
Gary for an illustration, here are two almost identical hulls built by the same builder. Both are 14x7. The first boat was built with 8” of taper (10” at the rear, 18” at the 12’ mark). The second boat was built with 9” of taper (10” at the rear, 19” at the 12’ mark). The hull with more taper (bottom) is 2” narrower at the bow, and you can see it’s a little deeper in the bow.
 

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Seven3 said:
Gary for an illustration, here are two almost identical hulls built by the same builder. Both are 14x7. The first boat was built with 8” of taper (10” at the rear, 18” at the 12’ mark). The second boat was built with 9” of taper (10” at the rear, 19” at the 12’ mark). The hull with more taper (bottom) is 2” narrower at the bow, and you can see it’s a little deeper in the bow.
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Thanks Seven! Appreciate the illustration. Have any info on the kickup?
 
I usually go to 2" on say a 6 cylinder sled or car engine powered hull, 4 cylinder I will kick it to about 2-3/4 but not drastic, more so at the stringers.
 
John Fenner said:
I usually go to 2" on say a 6 cylinder sled or car engine powered hull, 4 cylinder I will kick it to about 2-3/4 but not drastic, more so at the stringers.
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So on say a 13' - 14' sled for a car motor gearbox combo you're talking maybe 10" at the transom tapered to 12" -14" where the bow would begin to wrap up? I'm planning out a big sled and currently trying to figure out the design, as well as track down shop with the capability to brake the 12' sheets.
 
They certainly do. Unless you're talking about a palm beach hull. Not a brake in the hull side, but again at the chine. Bottom ___/ hullside
 
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