PDA

View Full Version : Trim Tabs?



champ
06-17-2015, 07:44 AM
I am having questions about my 17' Champion (similar to Sweet 16) porpoising. I am running a volvo 270 outdrive coupled with a ford 351 windsor motor. So with everything running good this year, this being the least of my worries I want to smooth out my ride.
The boats jumps out of the water easily to plane and when nailing it, it is smooth and flat. When at about 3000 rpm's it is porpoising. What I want to do is lower my rpm's to a comfortable cruising speed.
Any suggestions?

mattyboy
06-17-2015, 08:03 AM
porpoising is mainly caused by the prop. I ran several styles of props on my 16 each had a range that they would porpoise in . I found the solas prop had the smallest range that it would porpoise in. It may pay to try a prop then to drill holes and make room for a pump. Once I found the solas I hardly used the tabs.

BUIZILLA
06-17-2015, 08:58 AM
does your 270 have trim? if not, are you running it in the middle, or first hole?

champ
06-18-2015, 07:38 AM
does your 270 have trim? if not, are you running it in the middle, or first hole?

No trim on the 270. Running it on the second hole from bottom now. BTW Matty, It has the Solas on it now. (15x23)

mattyboy
06-18-2015, 08:12 AM
the solas was good on my 16 with 351w would only porpoise around 2100-2200 rpms 2300 rpm was a nice mid 2os mph cruise. weight would be the other factor move some weight forward and try the bottom hole. The solas is nuetral prop it doesn't give a lot of bow or stern lift. does the hull have any hook in it the 16 does and at slower speeds forces the nose down. for a small hull the 351 volvo is a tad azz heavy mine was . Tabs will hold the nose down and will balance load side to side. where is the tank ?

BUIZILLA
06-18-2015, 08:26 AM
the problem with that hull is the narrow transom area and the heavy engine combo.... not going to completely eliminate the issue

BUT, if that's your goal, get a set of 8x8 Lenco tabs