13 x 13 RH

Hi Rickard,

I'm not sure what prop is the factory spec, but a 13 x 13 was in the boat at the time it arrived here in Nashville. The HF7D Paragon is a direct drive unit, so the rpm of the prop would be the same as the engine speed. With 210-hp and a 13 x 13 spinning at 4000 rpm that equates to an unrealistic 49-mph in theory without slippage, take out 15% slippage for this particular deep v hull and that results in a realistic 41-mph speed with that prop.

Factory speed ratings were published at 38-mph with the 210-hp 327F and 36-mph with the 283 185-hp. Since this boat has a higher compression block than the original 8.0:1 of the stock 327F and the minimum power for that compression was 250-hp, I also have a cupped 13 x 14 speed prop I'm going to try. I think it's possible to get a little more speed, but clearly this is not a speed hull due to the deep V, it's a soft ride hull. Because of the additional wetted area of a deep v compared to a generally flat bottom design, the deep v always takes more power to reach a given speed (increased drag). I don't know the true power of this boat due to the fact that it has a higher compression automotive block. If power is in the 250-hp range, I may be able to exceed 45-mph with that 13 x 14 cupped prop. Otherwise it may just serve as a comfortable mid range cruising prop. For water skiing I'll probably stick with the 13 x 13.

The interesting thing is, a deep v is frequently the faster boat because of conditions. In anything more than a mild chop, my 1950s speedboats have to throttle down or pound. In conditions like this a deep v will just blast right on by.

If you can give me the weight, power, gear reduction, and prop, I'll run some calculations for you just to see what they say.

Regards,
Paul