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Re: TP Displacement Hull Board

Posted: Tue Sep 11, 2018 1:24 am
by nomastomas
"Plowing" is almost always a nose rocker problem. Entry rocker has to be smooth, continuous (parabolic) curve, with no abrupt changes. Smooth transitions can be can be hard to achieve in a shape with such short length. "Belly" or convex rail-to-rail curve doesn't cause plowing.

Re: TP Displacement Hull Board

Posted: Wed Sep 12, 2018 7:03 am
by krusher74
nomastomas wrote:"Plowing" is almost always a nose rocker problem. Entry rocker has to be smooth, continuous (parabolic) curve, with no abrupt changes. Smooth transitions can be can be hard to achieve in a shape with such short length. "Belly" or convex rail-to-rail curve doesn't cause plowing.
yeah I just did it far to much.

Re: TP Displacement Hull Board

Posted: Wed Sep 12, 2018 7:32 am
by GeoffreyLevens
I once had a Greg Liddle hull that was very deep. At least to my eye the rocker looked perfect. I wouldn't say that it "plowed" but it was difficult to get it started, to drop in on waves that weren't super powerful, and it just was not fast unless really in the pocket of a solid wave. Mush burgers were not my friend for awhile there.

Re: TP Displacement Hull Board

Posted: Wed Sep 12, 2018 1:05 pm
by nomastomas
All surfcraft have "form" drag, some more than others. Drag is not always "bad" and is required to achieve control. Question becomes "At what point, and under what (wave) conditions does that form drag become more of an impediment than an enhancement to performance?"
One of the advantages of using Aku to design/shape surfcraft is the ability easily quantify attributes such as "belly" or "V". Another is the ability to easily replicate those attributes. Displacement hulls are technically difficult to hand shape despite their simple appearance. It requires much more skill with a planer than I possess....

Re: TP Displacement Hull Board

Posted: Thu Sep 13, 2018 9:52 am
by GeoffreyLevens
nomastomas wrote:ADisplacement hulls are technically difficult to hand shape despite their simple appearance.
After shaping a fairly traditional fish shape and a Greenough style edge board (kneelo) I tried shaping a full on displacement hull board. Went to Mollusk surf shop and fondled several and once I really started to feel/look at them, nearly gave up right there and then. There is a LOT going on with those boards. Got a lot of help over the phone from Dale Solomonson who was a wealth of into and tips. My one and only attempt was rideable but I wouldn't give it any more than that.