boat prop and engine "freewheel"

[vipertblck]

Had a marina install new engine and go through outdrive and paid big buck to do so, they took it out on water for test drive and said all was good; showed me a short 20 sec video and all seemed ok. When I gave them the boat and when they water tested the boat, it had a solas 3 blade 15.5X13 prop on it, in bad shape, all chewed up and what not. I knew I needed to fix it. Anyway when I picked up the boat he suggested I put a 19 pitch 4 blade prop on it. I didn't spend the $150 for that at the time I picked up the boat. I ended up going to a prop shop and they say they had a 19 3 blade that I could try out, it was OLD though. So I put this on my boat and took it out for the first time today myself after getting it back with the new engine. Seemed to run just fine except when I got it to the right spot which seemed to be around 4000-4200 rpm and the trim pretty far in the down position, it would loose it all. By that I mean it acted like you just pushed the clutch in with a manual trans and the engine freewheeled. First thing I though was the coupler. But then when the boat slowed down after me immedietly pulling it into neutral, I hit it in gear again and it moved and planed out like everything was fine. again I tried a different trim angle, but still pretty far down. Right around that 4000 rpm mark it did it again. One thing to mention, this old prop I installed was a lot smaller overall diameter than the solas prop the marina water tested it with. My questions: could a different prop make this happen, and also if my coupler went bad, wouldn't I have smelt rubber, wouldn't it not move again after, etc.? I'm gonna have some strong words with that marina if the coupler is bad and there's not even 30 mins run time on the boat after receiving it from them....hoping' this is just the WAY wrong prop for the boat...

 

[foodfisher]

This different prop could be spun.

 

[midcarolina]

Spun hub on the test prop

 

[vipertblck]

What does this mean?? How can I visually confirm this?? I was hoping it was prop issue and not coupler, didn't smell any rubber when this happened, which I trout was a good sign. Anyway is there a way to tell on prop if the hub is spun just by looking at it?

 

[smokeonthewater]

make a mark on the inner splined coupler and the prop and run it... if the marks don't stay lined up it's spun

 

[vipertblck]

Do all props have hubs that could possibly spin? I ask this because the prop he loaned me was very old he said, not sure what that means or how old, but he just kept saying it was really old. Could an older prop not have a hub that could spin, or do all props have this possibility?

 

[smokeonthewater]

it most likely has a pressed in rubber hub and yes it can spin... most of the newer ones have square "hubs" (fuses) that you can change yourself in a minute or so

Why not put your old prop on and test it...

 

[vipertblck]

Put old prop back on and wow was it way slower, maybe 30,ph if even but the problem was gone and it held the power....think it's safe to say it was the prop

 

[Texasmark]

Do all props have hubs that could possibly spin? I ask this because the prop he loaned me was very old he said, not sure what that means or how old, but he just kept saying it was really old. Could an older prop not have a hub that could spin, or do all props have this possibility?

I never demolished one, even though I have one on a Turning Point Hustler prop, but the plastic/brass replaceable hubs look like they will break upon solid impact. On the older design hub which is pressed into the prop housing, it's friction fit and made of rubber. It will do just as you described.

I bought a used prop from a prop shop only once. Once was enough. Was lucky in that the owner had some integrity and upon my informing him as to the problem he allowed me full refund on a new one. But when the dust settled, in my mind he either knew the prop was bad or possibly had it in trade needing a repair and thought he had it fixed.

Mark

 

[vipertblck]

That makes me feel better knowing these older props are capable of doing this, "spinning". I nearly had a nervous heart attack on the river when this thing let loose. Then after reading your guys posts and my trial yesterday with the original prop, and problem not presenting itself at the 4000-4500 range...I feel a bit more at ease.