Blow out issue on a Crestliner

[biglurr54]

I have a 1989 17.5 Aluminum Crestliner. It has a 120 Looper on it. I am having trouble with turning. While at 3/4 throttle I cant turn much at all with out sucking in air and blowing out. The boat has Hydrofoils on it when I bought it. It also has a rough prop. The guy who had it before me didn?t have a depth finder so he used his prop. I reshaped the prop with and anvil and hammer is it came back to shape and it balanced nicely. It has a lot of nicks in it as well. I have the problem with the trim down as well as up. What should I do. I am looking at getting a new prop this year. I?m considering a stainless or a four blade. I?m beginning to like the benefits of the four blade. Which one would be better? Also should I remove the foils? Does that cause blow outs? Does a nicked prop create blow outs as well?

Thanks for the help!

 

[jonesg]

Re: Blow out issue on a Crestliner

I'm thinking that 120 is huge power for a 17' tinny.
What is the hull rated for?

 

[Silvertip]

Re: Blow out issue on a Crestliner

Crestliner, as do other manufacturers, build several models of boats in the various lengths. Depending on model, the boat can be eight feet wide from amidship to the transom. Hang an engine in the middle of the transom and then bank into a turn means the prop is like a pendulum on a grand daddy clock. It pivots upward in turns and can easily ventilate. The higher it is mounted and the wider the boat, the easier that can happen. Hull design can also affect this characteristic. A flat bottom boat doesn't bank like a "V" hull so a wide flat bottom would not exhibit this characteristic. This is a very common issue and the solution is to trim down slightly and back off the throttle a tad in turns. A damaged prop does not help matters.

 

[biglurr54]

Re: Blow out issue on a Crestliner

Its a Phantom Nodic. basically its a fish and ski. The boat moves with the 120. i have topped out at 49mph when I had stripped the boat. It had water logged foam that I scrapped out and had to replace all of the interior so when it was all stripped to the aluminum i put it in the water to see what it would do "naked". with everything back in the boat it does 42mph easily. when its low on fuel and just me in it I got 46mph. the boats placard is faded and just about un-readable. I found a sales flyer from Crestliner on ebay for 1989 and bought it. It is rated for a 125. Just made it! its a deep V and my father has the same boat with a 115 merc and his turns tight as can be and i have never seen it blow out.

 

[Bondo]

Re: Blow out issue on a Crestliner

and his turns tight as can be and i have never seen it blow out.

Ayuh,... He probably don't have a Beat-up prop, 'n whaletail either....

 

[LonLB]

Re: Blow out issue on a Crestliner

Fix the prop. IMO remove the hydrafoil too.

See how it performs. If it still does it, you can try lowering the motor a hole or two. Check your speed with a GPS. If you lose 1, 2, or even 3 mph dropping the motor, it might be worth it to have better handling.



If it were me personally, I'd drop the hydrafoil first thing. A motor that big should have NO problem getting on plane, and will carry the bow fine too.

 

[biglurr54]

Re: Blow out issue on a Crestliner

4 blade or 3 blade stainless or 3 blade aluminum?

 

[biglurr54]

Re: Blow out issue on a Crestliner

My plan is to drop the foils. i never really liked them to begin with but thats how the boat was set up when i got it so i figured dont fix it if its not broken. But i guess it is broken if you try to turn! im shopping for a prop now and im not sure what to get. Ive read so much on 3 blade vs 4 blade and aluminum vs stainless vs composite. it currently has a 13 1/4 x 17 prop on it. im considering unloading the motor cause it a 1989 and putting on a 13 1/4 x 19 so the motor doesnt have to work as hard. I under stnd i can run the chance of over reving it by dong this but I hardly ever run wide open. Only to test top speed once a year to make sure everything is status quo. what do you guys think?

 

[Bondo]

Re: Blow out issue on a Crestliner

it currently has a 13 1/4 x 17 prop on it. im considering unloading the motor cause it a 1989 and putting on a 13 1/4 x 19 so the motor doesnt have to work as hard. I under stnd i can run the chance of over reving it by dong this but I hardly ever run wide open.

Ayuh,... The way I read that, you've got it Exactly, Backwards....

lowering the Pitch, Increases the rpms...
17" to 19", increases the pitch, lowering the rpms,...
probably lugging the motor...

 

[steelespike]

Re: Blow out issue on a Crestliner

Yes; the motor needs to rev easily within its rpm range.The whale tail is there because it was watertlogged and likely slow to plane.I'd get the prop tuned up right.remove the foil and make some test runs and get back to us with the details.

 

[Lion hunter]

Re: Blow out issue on a Crestliner

Just for giggles I would weigh your dad's boat and your's. I would also try and immulate his set up. I'm guessing that the with the rebuild you lightened up the boat quite a bit and that hydrofoil is lifting it out of the water.

 

[mrmamiller]

Re: Blow out issue on a Crestliner

I have a Crestliner Nordic 18 (aluminum). Put on a different prop with identical specs, but not OMC. The prop blew out bad. Went back to genuine OMC (aluminum) prop and all is well. I now have a new Michigan paper weight in my office.