Tower of power!!!! Old starcraft.

[Papafluff]

Re: Tower of power!!!! Old starcraft.

I wouldn't say she's plowing. Water is coming of the sides about a little less than 3/4 the way back

 

[canoemang]

Re: Tower of power!!!! Old starcraft.

you have the motor mounted at the correct height?

That thing should scoot with that TOP hanging of the back...

 

[Chris1956]

Re: Tower of power!!!! Old starcraft.

OK, 3/4 of the way back is not plowing, but not optimum. You need to get that nose up. Your trim working correctly?

 

[Papafluff]

Re: Tower of power!!!! Old starcraft.

Trim is working sweet but as wired said I need to raise motor. When I'm WOT and trim motor up the water is catching the front of cavitation plate and I would assume cause a lot of drag thus pulling bow back down? No matter where trim is set I get a lot of spray coming off the motor. The plate is now 3/4" above bottom of boat. Raise another hole? What do you think my top speed should be if I get this set up right? This is not a heavy boat and I would think that TOP should push it faster than 45 or am I wrong?

 

[Papafluff]

Re: Tower of power!!!! Old starcraft.

Thank you criss for sticking with me on this and I thank all of you for your replies and advice

 

[wired247]

Re: Tower of power!!!! Old starcraft.

Yeah, I'm not really sure why anyone would think installing the anti VENTILATION plate even with the hull bottom would be a good idea but its one of those things that gets repeated so much that some people believe it.

 

[Chris1956]

Re: Tower of power!!!! Old starcraft.

Well, My speedboat with a 150IL6 used to plow water and still achieve 45MPH. After I trimmed it up it was good for 55+MPH. Depending on your hull shape, you should see mid fifties, I would think, at max trim....Remember, small course corrections and watch out for chine-walking. It can be easy to flip over if you hit a wave.

 

[Bob_VT]

Re: Tower of power!!!! Old starcraft.

Trim is working sweet but as wired said I need to raise motor. When I'm WOT and trim motor up the water is catching the front of cavitation plate and I would assume cause a lot of drag thus pulling bow back down? No matter where trim is set I get a lot of spray coming off the motor. The plate is now 3/4" above bottom of boat. Raise another hole? What do you think my top speed should be if I get this set up right? This is not a heavy boat and I would think that TOP should push it faster than 45 or am I wrong?

Nope you are at your max speed. It's the hull and the rivets. Look at evinrude performance reports or yamaha or even mercury and you will find that 115 hp are right at the 43-45 mph and you will also see that the aluminum hulls are slower then the fiberglass hulls.

It's just the nature of the beast.

 

[wired247]

Re: Tower of power!!!! Old starcraft.

Look at evinrude performance reports or yamaha or even mercury and you will find that 115 hp are right at the 43-45 mph and you will also see that the aluminum hulls are slower then the fiberglass hulls.

It's just the nature of the beast.

He's got a slightly lower compression 1500. Thats what that late Merc 115 is. Crank HP is in the 145 HP ish range. He has a lightweight , small boat. If he can get that motor up high enough ( which is difficult to do with "20 inch" mid TOP's )and the transom is strong enough to hold the motor there is no reason he shouldnt be hitting the mid 50's. Ive gone 54 GPS with a crank rated 90 Johnson in a heavier boat. The numbers you are referencing are for larger vessels and arent propped for speed. Decent setup can make up for brute power.

 

[Papafluff]

Re: Tower of power!!!! Old starcraft.

Wired
That's what I thought. This is nothing but a glorified row boat. How does raising the motor account for so much more speed?
Humor me I'm a total newbie. I've been using boats my whole life but never got into the going fast part of it and I'm loving it

 

[Bob_VT]

Re: Tower of power!!!! Old starcraft.

Trust me........ I speak from hands on Starcraft experience with oversized powerplants.

 

[wired247]

Re: Tower of power!!!! Old starcraft.

Wired
That's what I thought. This is nothing but a glorified row boat. How does raising the motor account for so much more speed?
Humor me I'm a total newbie. I've been using boats my whole life but never got into the going fast part of it and I'm loving it

It allows you to get the bow and stern out of the water. That long *** TOP lower unit is dragging through the water like a sail pulling the rear of the boat down. Get it up high and you lose the frictional resistance running through the water and you gain leverage on the water. You can push the bow higher to the point where theres only a foot or so of the stern in the water at higher speed even with a hull design that is marginal at best.

Prop 4-5 inches below the hull at most. 19-20 pitch prop. Hang on.

 

[Papafluff]

Re: Tower of power!!!! Old starcraft.

Wired
I'm going to try what you suggest can't wait to see. Don't worry about my transom it can handle it I've beefed it up pretty good
I really am just trying to see what I can get out of this boat. I don't plan on leaving this motor on it but its the only boat I have right now so I just wanted to play. Which brings up another question. What's the best boat for this TOP in regards to performance? I'm gonna buy another boat for this motor but want to draw on everyone's experience before I make a choice. Again I thank you. The knowledge that's available here is awesome

 

[Papafluff]

Re: Tower of power!!!! Old starcraft.

Should I start another thread for this last question. Like I stated before new here. Any advice is always welcome and appreciated

 

[wired247]

Re: Tower of power!!!! Old starcraft.

Wired
I'm going to try what you suggest can't wait to see. Don't worry about my transom it can handle it I've beefed it up pretty good
I really am just trying to see what I can get out of this boat. I don't plan on leaving this motor on it but its the only boat I have right now so I just wanted to play. Which brings up another question. What's the best boat for this TOP in regards to performance? I'm gonna buy another boat for this motor but want to draw on everyone's experience before I make a choice. Again I thank you. The knowledge that's available here is awesome

Theres lots of 70's and 80's hulls that you can get for dirt cheap that will fit the bill. Look for a Checkmate Enticer or Predictor. They are good solid pad bottom boats that will easily handle 70+ MPH. Or you could do a 70's Glastron or its many clones of the James Bond type speed boat. The world is your oyster when you start looking for 70's and 80's hulls that need motors and interior work for under $1000.

No one makes small ski/speed boats any more. Now its all bass boats, bayliners and those ridiculous wake boats.

 

[Papafluff]

Re: Tower of power!!!! Old starcraft.

With the proper boat and proper motor set up what can I expect to achieve with this TOP?
Wired again I thank you for all your advice and knowledge and for sticking with me on this thread
Also thank you for accepting me as a friend. I love to draw on other people's knowledge on something I'm new at and I'm sure ill have many more questions to come

 

[wired247]

Re: Tower of power!!!! Old starcraft.

The late TOP's are good motors. The power port piston inlines are a cross between a crossflow and a looper. They have a much better , modern style ignition system than the older distributor style ignitions. Its an honest 115 HP 1.6 liter motor and with a lightweight good hull and a a good prop should put you at or around 60 MPH.

With the proper boat and proper motor set up what can I expect to achieve with this TOP?
Wired again I thank you for all your advice and knowledge and for sticking with me on this thread
Also thank you for accepting me as a friend. I love to draw on other people's knowledge on something I'm new at and I'm sure ill have many more questions to come

 

[Chris1956]

Re: Tower of power!!!! Old starcraft.

Papa, 60MPH is optomistic, IMHO. However, low 50s is certainely achievable.

 

[wired247]

Re: Tower of power!!!! Old starcraft.

I ran 61 mph with a low compression 1500 . Basically the same motor as his late 115. That was with a 21 pitch prop and a 1100 lb ( without motor ) boat, my 230 lbs and my kids.

Same boat with a 260 Merc ran 77 MPH before I chickened out. Same boat with a 225 Merc 3.0 ran 74 MPH. Same boat with a slightly modified 90 Johnson ran 54 MPH. Same boat with a slightly ported 140 Johnson ran 63 MPH. Same boat with a 105/150 Merc Jet ran 45 MPH. Replaced the jet with a prop lower and it runs 64 MPH. I'm building a 200 magnum for it right now. I'd expect an easy 70 MPH at 7000 with a 19 pitch prop.


Get your motors up people.

 

[mr 88]

Re: Tower of power!!!! Old starcraft.

"I'd expect an easy 70 MPH at 7000 with a 19 pitch prop." Are you saying the OP should hit that number with his setup [ if propped out and jacked enough] and his red line is 7g ? Your first paragraph has me scratching my head a bit.I am running a fresh rebuild 78 1500 with new hi-domes and hit 54 gps on a 15' 1966 Power Cat dual tunnel hull that weighs in at 425, me at 190 and two tanks of fuel on a 20" at 6g with the motor raised 1" 1/2 off the 15" transom. Do you have a pad on it ?