trim tabs for speed

[bonewar]

ok i've herd on the grape vine that the trim tabs on the sv27 aren't in the right place for speed, i have been told that they should be closer to the strut because the boat at full throttle only sits on a very small area of the back of the hull. so having the trim tabs closer to the strut sort of makes sense does anyone know about this, thanks bonewar

[rocket-ron]

I was told by a very experenced racer that the trim tabs "only come into play" when the hull is is pitched,either side to side or fore and aft. I was also told that getting the tabs,to be flat with the hull bottom(by elongating the mounting holes,to move them down) wasn't needed,or really the right way to set them up. He said you want the base of the tabs about 3/32-1/8 inch high,and have only the trailing tips(very ends) of them contacting the water. Having the whole tab in the water,even if level with the hull bottom,just creats more drag,since they are allways in the water. Ron

[Mich. Maniac]

Actually yours do look pretty far apart. On stock sv strut there isnt much adjustment compared to your higher dollar strut. With that being said I feel there is more to be accomplished with adjustable trim tabs and stock strut. They seem to be working out fine the the stock position "mounting holes" and could easily handle more speed. I just dont think my wallet can handle much more speed!!

[Scott T]

In an article I read (written by John Finch), tabs close to the centreline (inner tabs) control the ride on the straights, and tabs further out control the ride through the turns. The article doen't give a specific dimension from the centreline, but does mention 1". So if youre are much further out than that, they're probably not doing anything on the straights.

The "inner tabs" are also useful to counteract any prop torque, i.e. stop the boat leaning over to the right on the straights. Just tweak the right tab down a fraction lower than the left.

Cheers,
Scott

[Avanti]

Those water pick-ups seem too far outboard to be useful at speed, have you noticed any cooling issues?

I like the though hull design and have be planning on doing it myself.

[rocket-ron]

I haven't had any heat issues with the rudder pickup (stock location) sofar. When I first got my SV27 I noticed a little less water comming out of the exit on the side of the hull,at lower speeds. I found the tubing inside the radio box,had a small area that was "kinked" in a bend on the line going from one side of the cooling jacket (ESC) to the other. I replaced the tubing,with a longer peice,and made larger turns in the tubing. Water flow has been great ever since. Ron

[Avanti]

I meant the black pick ups on the bottom of the hull. What are you using them for?

[bonewar]

water pick ups

avanti mate, they are indeed water pick ups, where they are placed works fine , at low speed and high speed( boat sits on about 1-2 '' of the hull at full speed) water is always exiting the hull, i changed to these style from the rudder pick up to acheive better water flow through the motor and esc and less drag from the rudder. not to shaw on the less drag issue though. have a look at page 4 pic 1 of ( show us your sv) thread it shows you how i put them in the hull. mich those trim tabs on my upgraded sv27 are in stock position.what i wanted to know , would putting another set of trim tabs inside the original ones would help with keeping the boat trimmed at speed.