STV srint chine walk at 100 mph

[darknet]

I have a 86 STV sprint bottom that is 425lbs with a 20" 280 offshore mid ,cle 4 hole big skeg. I am 8" back running a 28 ET lightning. My prop shaft is even with the bottom of the boat. At 100 mph I am at 7500 rpm. The problem I am having is it starts to chine walk at that speed. I have tried a few diff props like a chopper two 28p, a Trophy small hub 4 25p. I am unable to air the boat out because of this chine walking. It wants to keep going faster but it would be a wild ride if I did. Some seem to think I need a prop that does more pushing forward with little to know bow lift and no boat twisting effect. They seem to think that those two things are causing the chinning. Any advise as long as it helps would be great. Thanks Dark

[strongback]

Hi Dark, I am no expert but have experienced the same thing in my first STV. It freaked me out too but I got it worked out with some help from the guys here on SnF. Mr Tom Foley and Dave Deeznuts simpely walked up to the front of my trailer and peeked under the hull for about 2 seconds each, only to tell me YEP ya need to go up another inch. I did what they said and had success. Ill pass on what worked for me. With that 8'' of setback you can run higher and should, these boats don't like even with the pad. They like higher settings with that much set back. Id try out 1'' up and keep going up from there. If its not a center seat/steer and has a passenger seat up front, try throwing 30-50 pound sand bag on the passenger seat if your riding alone. Id also get rid of the trophy and that chopper. STV's and most hi-po small boats do real well all around with a ET style prop. 28''p is a good pitch for my rig. It can get you up over 100 and carry a load if you need it to. Keep your eye on the water pressure gauge as you raise the motor. Im sure other guys on here will pitch in with all kinds of help. They are a good bunch...... Good luck

[petehubbell]

I have the same boat. Here's my two cents. 1.5" above the pad. Try to find a cleaver in the 30 pitch range.

Is the boat center steer? 425 lbs is really light..... Good luck and be safe. PH


Post some pictures of the boat

[BeefKid]

my mirage did that at 108 was told its trying to get on top of the case... raised the motor and it felt fine

[BRB]

Amazing every stv ever put on here is a 425lb or so light layup...drives me nuts...cause its a stv doesnt mean its 425lbs dang

[strongback]

Hey BRB do you always have to whine about this one? .....drives me nuts..... just because its a STV related post don't mean ya have to read it........

[BRB]

Well yeh....cause weight has a factor in set up prop selection...and Selling price...so there ya go

[strongback]

BRB Since you are here on this post ''why'' don't you add some useful information for the guy since your the expert? Why not help a new comer out that asked a question of us instead of the negativity? Maybe his boat is actually 475 pounds and just go off of that? BTW I appreciate that PM ya sent me a few minutes ago! Classic.

[petehubbell]

I'm still hoping to see some pictures of this "tater chip"

[TripleA]

I agree with everybody on the motor height. I had a lot of problems with my STV setup. Mine is a different bottom but after some STV experts advise I raised motor to 1 3/4 above pad and worked perfect. I run Yamaha drag style props. 425lbs and a bow lifting prop could = bad, easy on the up bottom.

[BRB]

Bingo triple a.....sprint bottoms are flighty at speed also....so my point was a novice with a true 425 sprint bottm wrong prop could end up real bad

[STV_Keith]

Amazing every stv ever put on here is a 425lb or so light layup...drives me nuts...cause its a stv doesnt mean its 425lbs dang

My 92 Pro Comp Ski with ski bottom weighs 850# bare. So there, DOUBLE the weight of every other one ever talked about on S&F.

Darknet, I know everyone else on here will tell you to run an ET or a cleaver, but my boat likes a full round ear Mazco RE-3 the best for all around. Faster cruise (less slip), and more bow lift, so less positive trim to get it to fly. Yours is quite a bit lighter than mine, but I'm gonna GUESS that the sprint bottom doesn't develop as much natural bow lift as the ski bottom did...where a round ear prop would help you out some. Give it a try...can't hurt.

And mine is 6" back and 1-1/4" up from the pad.

[darknet]

Thanks guys for all the advice, I am sure I will get it to stay stable now with your help. And by the way it is center steer and it does weigh 425. Sommerford built two of these boats that were just alike for two twin brothers in texas, they were the two lightest boats he ever built that he sold to the public. That's the story I was told. Research it and is true to my findings. The Kevlar bottom and one 2 oz matt layup for the cap is to blame. Thanks again.

[cody620]

I have a 87 sprint hull STV with a 10inch setback, the motor height is 1 3/4 above the pad with a 26 et and a 30 et
Hope it helps

[dumbnfun2]

Hav u personally weighed it ? Does it seem as if the boat is flexing ? Might need to check the hull ... Boat is almost 30 years old b careful .... Just my opinion ....