Round chine lift and roll

[sailor1]

Don't even know if this belongs here, but here goes. I have a 1970 Viking, 38ft, sports sedan. I am repowering and restoring it. I am putting J&T 671ti, rated 410hp. It will weigh about 25000lb loaded. For anyone that doesn't know it is a round chine boat, and has a waterline of about 34ft. The problems I have are that it rolls easily and it will plane but not without some effort. I was told if I added spray rails which went below the waterline for five feet or so it would lift the nose quicker. I was also told if I added a strake one inch high and two inches wide on the chine it would help the roll. Any advice or comments would be appreciated

[gonzo]

Spray rails modify the flow of water and the dynamic lift. If you install them, it is crucial that they are the right size, shape and location. For example, a sprayrail in the bow can ventilate the hull reducing lift and creating other problems like listing at certain speeds. Is the person recomending you to install the rails knowledgable? Round bilge hulls roll, it's their nature. Some of the solutions to reduce the rolling are planers, damping tanks and bilge keels. I'm not sure a spray rail would do much for dampening. Actually, it may start a cycling roll that will make it worse.

[sailor1]

Yes the person is a licensed wood boat builder. The 1x2 flat on the chine is similar to a planing surface, but I have been told the wider I make it the less effect it will have on roll. The example he used was to take a 1x2 and a 2x10 and swing them through the water on the 2 inch side. Have not tried that yet. He also said the wider I make the on a round chine the less likely it is to plane. The spray rail and the chine strake are two seperate pieces.

[gonzo]

I think that if he gives you a written warranty, like a reputable designer or builder would, you'll be OK. Building or modification contract usually have a minimum speed and or boat handling charcteristics clause. If he is not willing to put it in writting, he may not be so sure of the veracitiy of his claims.