sharp chines

[Bill Perkins]

Couldn't find the thread with the search engine but I thought it had been stated here that sharp chines as opposed to those rounded over gave superior performance when on plane . If so ,how sharp is sharp? I've been stropping away with a long board and 25 grit in preparation for laying my cloth and mine are shaving sharp .I'm thinking the two layers of xynole I plan at the chine would slightly round over this profile, and be strong enough to protect it ;or should I round over the chines to about a 1/4 in. radius before laying the cloth ?

[mmd]

You will need to round over the chine to get the cloth to lay properly without bubbles. The radius of the round-over is dependant on the weight of the cloth, but 1/8" radius will probably be fine.

If you want to squeeze the outer limits of performance of your hull (probably an exercise in futility unless you are a.) planning to race the boat and b.) willing to do the dozens of other repetitive super-tuning chores associated with powerboat racing) you should mould the chine after 'glassing with fairing compound to achieve an edge that you can shave with. The cleaner the water seperation from the planing surface, the less drag induced. Maintaining a clean edge is quite another task.

[Bill Perkins]

Thanks for clearing that up . The long board is beating me up . I feel like I've been bested in a wrestling match . Easing that last 1/8 th in. should be light work .

[Bruce Hooke]

On the off chance that you don't already know this: just make sure you are happy that the line of the chine is fair BEFORE you start the rounding over process. It's a lot easier to fair a sharp corner than it is to fair a rounded edge.

Also, you may want to do a trial run on some scrap material with your specific xynol cloth and googe to make sure that it will lay down well over the radiused chine.