Help with PT SS45

[David Kingston]

Folks, just wanting to get some tips on how to bring down the left sponson on a Phill Thomas SS45.

Notes on setup....

Boat is setup as electric.

COG is a tad further foward than what Phil recomends.

There is no twist in the hull, but i have cut the double skin out layed some more carbon fibre in the bottom and added 10mm engine rails and motor mount.

There is also a carbon Fibre rod right across the boat (port to starboard) to stop any flex.

Fin i a Dick Tyndal.

doenst matter what prop i run, the boat still did the same thing. (x448, x648, x450, x450/3)

Running the boat is a dream. I really should not be to worried. Turns flat and fast. Stability in corners is great and there is no bog down. In the straights however the left sponson is lifting out of the water. Its not that big a deal as its not even looking like blowing over. I can keep it up almost the entire length of the straight. I have been fortunate to have perfect to moderate water conditions to test in, but im worried that if im chasing and i turn under someone with the boat already off the water there might be a chance it will catch that left sponson and flip.

I tried mounting batteries on the left and this didnt work.

I put about 300grams of weight on the sponson and that didnt help much. (bounced a bit in straight)

Slight adjustment on turn fin to bring nose down. Nothing Just turned harder.

Any one got some ideas.

Thanks

Dave

 

[SayMikey]

I put 6 oz in the end of the pool noodle and push it all the way up in the left sponson

 

[P THOMAS]

The Tyndall fin is setup at 90 degrees not at an angle. The curve should be parallel to the water line. Dont try to adjust the ride with the turn fin.

Maybe the turn fin side is sucking down lifting the left side. SO what does it do if you turn left with the power on full? If it spins or blows off the turn fin is not parallel to the sponson pads.

The turn fin MUST be straight or tweeked in abit at the rear.

Check it out, test some more.

Maybe just a touch more strut angle too will help. Every boat is different, have to run it to see what trim is needed.

Cutting the engine well out will allow the hull to flex. You think it is straight, maybe not any more.

 

[GUPPY]

David could you show pics of your set up.......I too have a PT45 SS and going to electric

 

[David Kingston]

Phil

Yeah its straight. I made dam sure of it.

As for turning left. It doesnt like it much at any power level. It is able to but its not like it will go round the course backwards at full throttle.

I havent really even started to tap into what potential the boat has. The motor is seriously underpropped. I'll pay around a bit more with it. I know that there are some other props that i really want to test.

As i said the left sponson is only just off the water. Definatly see it clearly at water line whole length of stright. At peak it would be 5-10mm off the water.

I do know that i need to make a stronger turn fin bracket. The 4mm one on closer inspection is starting to bend. If it wasnt for checking the turn fin again to put it back to level i wouldnt have noticed. Got some nice 6mm stuff that will do the trick.

guppy.

i will take some photos of it for you.

Dave

 

[RodneyPierce]

Dave, thats perfect!!!! Loose is fast, but on the verge of out of control. My PTSS21 sponsons ride above the water surface also I would say a good 75% of the time. The fin really does most of the holding the boat in the water on mine. And I actually do use the fin to make fine adjustments to the ride attitude of the boat. I have found that works much better FOR ME then trying to re-prop or adjust the strut when I have the boat near perfect. I use the fin to loosen the boat up for smoother water, and tuck it back a hair to tighten it up in windy or rough conditions.

 

[LarryConrad]

Mine has a front radio box,12 oz. Sullivan tank in the starboard sponson, 2oz, hopper in front of the engine, approximately 6oz of weight in the front of the port sponson.

Larry

 

[P THOMAS]

You guys test more than i do Im sure. I have too many boats cant spend enough time on just one HA.

Yea I wouldnt worry about the ride unless it starts spinning or blowing off unexpectedly.

Make a stronger turn fin mount and check it agian. Make your self a tool about 30cm long and as wide as the space between the fin and inside of the sponson. You can see the angle of the fin, bend or shim it it in so the fin is past straight and try it. The boat could do figure 8s but it dont like it. The boat will just sit down hard on the water turning left if the fin is right.

 

[El Zorro]

I have 2 1/2 ounces of stick-on wheel weights on the rear of the left sponson on my PT Sport 40, and it probably could use more. The boat still "sponson walks" down the straightaway when the water gets roughed up but goes flat around the corners when the turn fin is hooked up. The Center of Gravity on my boat is 1 inch behind the rear of the sponsons, but I think the boat would settle down more if it were farther forward. Go out and buy some stick-on wheel weights and go test at the pond. The boat will let you know if you make a good change or a bad change. Set the turn fin up like Phil said in a previous post. Guess I don't have to suggest what turn fin to use in this case.....................

Dick Tyndall

 

[lohring]

That sounds like a torque problem. As many others have suggested, weight in the left sponson is the solution. Nearly all sport hydros use that solution. When I converted a nitro 1/8 scale to electric, I put the battery box on the left beside the motor. That was a little overkill, but it worked.

Lohring Miller

 

[wayne middlemiss]

dave as it has been refered to in regards to tourqe of the engine causing it to carry the left sponson that would be my tip also.

i run an ac sport 40 and it had issues with the turnfin not being truly flat when sitting on flat surface, it was only a very slight bend in the fin which gave it hell, you could not get the boat upto speed without it doing a wild dance , it was just not usable in that state.

so issues was resolved with a new fin made in the mill totaly,

i dont use rolled turnfins on sport 40.

wayne