gaining speed from setting back?

[Talon2.5]

ive always been working on the looks of the boat and have not messed with the talons set-up till now, i'm looking for a few MPH more

i put in these 2" setback spacers but am getting feedback that it will only help the wieght handleing characteristics of the boat

just wondering if a tunnell with a center pod is going to gain any speed by doing this and maybe even a few inches more in the future

figured i would post this to get some more feedback as to what worked for you

[Racemore]

I'm not sure how much if any setback is built in to your boat.I would say if you run your boat and to get the best mph you have to use positive trim beyond the gearcase level in the water than you could stand more setback.To get a top speed may take away from the hole shot.With the notch Hydrostream has built in to the transom a 10" jackplate gave the best top speed but didn't seem to be as quick.Heavier boats need setback,when the boat is flying in clean water at top speed and your trim is set where you have level-straight forward thrust your as good as it gets.If you have to trim to lift you are leaving some speed on the table.My Opinion.:cool:

[tunnelmike]

he's on the money. Your hull and prop combo are where the lift should come from. When you don't need trim to run at speed you WILL pick up MPH.

[Talon2.5]

no i dont need trim to get speed over the negative trim spot, at speed my motor is straight and flys nice, if anything i do hope the spacers help a porpoise that happens around 36 mph if your just putsing along, it never porpoises if ya nail it out of the hole and hold it

just was curious of what set-ups others with tunnels and center pods gained or lost through set-up changes

[AnthonySS]

...will not help top end...only helps to lever and the bow for loads.

[Racemore]

There is a point it does untill doesn't.That is why setback is built into boats.In most boats say you have a rider and you get to top speed and the rider goes to the back of the boat you'll go faster.The STV has a notch transom that shouldn't need any plate at all if you ask Rorke or Rusty but some guys prove that it does in their application.Just like moving fuel tanks,batteries,...Also setback from the running surface allows an adjustable range of efficency.:cool:

[Talon2.5]

sounds like what ive heard, my main thought on the spacers was to ghange the CG to see if i could change the arm to pull back some away from a rocker built into the forward area of the center pod to curb the porpoise problem, so it looks as though that may work ?

thinking out loud to see if i'm right in my original thought

[Corona Mike]

Skip,have you tried running the boat with the extra set-back yet?If so,did you raise the motor?Let me know.I'll be talking to Bob Icenogle in the next couple of days,and i'll ask him if he has had any experence with your boats set-up.Also I need to bring you some Keys pictures to post for me.Let me know what you are doing maybe on Sunday.Thanks,Mike T.

[MN4V]

Could the porpoise be from not enough hydrodynamic lift at 36 mph? The boat runs along and lifts up to 6 or 8 degrees and it produces enough hydrodynamic lift to bring the bow down which in turn brings you back to the point of not enough hydro lift again and it keeps going though this cycle until boat speed is increased.
If this happens when your accellerating it can be a ton of different things. Prop, weight, etc.
Mark N

[Talon2.5]

corona mike, no have not run it again since putting in the plates, we took out the hydraulic ram and hydrostreamdave is machining a jack screw set-up to replace the ram and make it a manual plate, right now there is nothing stopping the motor from sliding up and off the back of the boat if i hit a wave just right and it pops up in the slides it could come out :eek:

but.....may wire it in place to try sunday??? :D

MN4V, makes sense!! we will have to see what the setback accomplishes with the porpoise if anything at all but what you said makes sense to me :)
if you take off balls to the wall and stay in it, it never porpoises but if you just take off and try to cruise 50 mph it will do it