strut adjustment question..

[kwiktsi]

OK, this has been bugging me for quite some time now- I have always been told that RAISING the strut will pull the prop out of the water (obviously) and lower the hull into the water, causing it to run wetter. LOWERING the strut will submerge the prop and the lift from the prop will raise the hull out of the water. This is what I was told by Chris Fine years ago and what I felt to be true from my experience as well. I have read here and on other forums that it is the opposite- raising the strut will raise the hull out of the water. I just don't understand how this could be true . So, which is it??

[madmikepags]

what kind of hull???

[madmikepags]

it depends on the hull and type of prop

[madmikepags]

cats hydros riggers and monos all are different and then there is the angle of the strut too??????

[kwiktsi]

I'm talking mainly cats, sorry, forgot to mention that. I'm aware of the differences the angle makes, I'm more curious about actual strut height changes. Thanks!

[madmikepags]

if you drop the strut and you have a prop that has lift it will push the rear of the boat up and the bow down, thats the only way i see it doing that.

[Rocstar]

Think of it this way... The prop stays the same depth in the water, lowering the strut will raise the transom bringing the bow down and raising the strut will lower the transom bringing the bow up. There is more to it, but this is a simple explanation.

[kwiktsi]

Think of it this way... The prop stays the same depth in the water, lowering the strut will raise the transom bringing the bow down and raising the strut will lower the transom bringing the bow up. There is more to it, but this is a simple explanation.

That's what I thought, so on a cat (or hydro) where it is riding on air, wouldn't a lower strut make the whole boat run looser (even more so with some "up" trim)? I know on my hydro, it would run quite a bit faster with the strut dropped down a bit vs. raising it. I see so much mixed info on this on the web- some sites say raise the strut to loosen the boat, others say to drop it. Thanks!
Joe

[Heaving Earth]

That's what I thought, so on a cat (or hydro) where it is riding on air, wouldn't a lower strut make the whole boat run looser (even more so with some "up" trim)? I know on my hydro, it would run quite a bit faster with the strut dropped down a bit vs. raising it. I see so much mixed info on this on the web- some sites say raise the strut to loosen the boat, others say to drop it. Thanks!
Joe

It's a question of finding a happy medium between speed and stability.

[kwiktsi]

It's a question of finding a happy medium between speed and stability.

I agree with you there, I'm just trying to figure out which is right and which is wrong in regards to strut adjustment. Example, the miss geico 29 I just bought, popular thought to stop the bow from bouncing is the raise the strut and add down trim. Isn't that counter productive and just making the boat run wetter?Wouldn't lowering the strut and possibly adding some down trim from there have the same affect on ride angle yet run a bit looser/faster up top?

Edit- just to clarify- by faster, I am talking mph, not lap times.

[Rocstar]

I agree with you there, I'm just trying to figure out which is right and which is wrong in regards to strut adjustment. Example, the miss geico 29 I just bought, popular thought to stop the bow from bouncing is the raise the strut and add down trim. Isn't that counter productive and just making the boat run wetter?Wouldn't lowering the strut and possibly adding some down trim from there have the same affect on ride angle yet run a bit looser/faster up top?

Edit- just to clarify- by faster, I am talking mph, not lap times.

In a cat hull the adjustments are needed to "air out" the hull and get her flying level without running wet or blowing over. Lowering the strut and adding negative angle will most likely cause the hull to run very wet. Every hull is different, it' really a matter of trial and error.....

[Gabe_k]

for a cat, the happy medium is having the strut aligned with the transom.. raising it will cause it to ride higher/lighter/faster but will be very unstable and more blowovers.

[kwiktsi]

See, that's where im confused, how does raising it cause the boat to ride higher? By dropping the transom and allowing the bow to come up? If so, how is that looser than lowering the strut (raising the transom) and giving a bit of up trim toraise the bow as well? My thinking is that would allow the whole boat to ride higher out of the water like that and that is how it was explained to me. I know my boat ran faster with the strut dropped and some up trim than with it raised and neutral trim.

Now, back to the miss geico- it likes to bounce. The popular fix I see is to raise the strut and give down trim. If raising it will lower the transom and raise the bow, then you are using the down trim to push the bow back down. Wouldn't just dropping the strut work better and still keep the transom from "dragging" so much, then add a touch of down trim if the bow is still high and bouncing make for it riding more level and a bit looser overall?

[785boats]

kwiktsi.
Does this help any?
Go to 'Technical Tips' at the top of the page & then click on 'Strut Adjuatment'

http://www.ppbracing.com/index2.htm

[BHChieftain]

Hi,
It is generally true that lowering the strut raises the transom and loosens up the boat. But every boat is different, and the Miss Geico hull has its own particularities-- one of which is the front of the boat acts as an inverted wing and lifts the front of the boat a lot more than other "standard" cats-- so the boat does not run "flat".

If you wade thru the original Miss Geico threads (the hull is the same between V1 and V2), you'll see a lot of posts on how to minimize bouncing, and the best combination for *this* particular hull is strut up as high as you can without cavitating, and batteries towards the back. This results in the cat running with the nose pretty high, mostly on the back 1/3 of the sponsons, and you get pretty good speed at that attitude. If the boat were to run "flat" along most of the sponson length, then raising the strut would really slow it down... but that isn't what happens with this hull.

Chief