Hydrofoils

[eatropefish]

'83 Tracker III with '87 Mariner 45hp. 10x13 alum prop. Slow and difficult to plain especially with two people. Having my buddy sit towards the casting deck helps but if I lose speed then it's hard to get going again. I've played with the trim while accel but no good. At times it feels like the prop is breaking loose. Could this be extreme cavitation? What are your thoughts on installing a hydrofoil?

 

[Silvertip]

Re: Hydrofoils

Did this just happen or is the boat new to you? If you've owned the boat for awhile and it's not done this before, then adding a hydrofoil is a band-aid. Determine what the problem is. Make sure the engine is performing as it should. If it's not, a tune up including compression check, carb cleaning and rebuild would be a starting point. The cavitation you mention could very likely be a spun prop hub. The rubber between the hub and the blade area of the prop can come loose so the inner hub spins within the blade area -- hence "no push". Put a mark on the hub and another mark on the blade area directly in line with the first mark. Run the engine until the "cavitation" or engine reving occurs. Check the alignment of the marks. If they are no longer lined up the hub has spun.

 

[georgiaboy]

Re: Hydrofoils

I would agree with Silvertip that something may be wrong with the engine. My 82 16" Tracker with a '82 45 Merc. goes right along but it is not loaded down with a lot of toys. Weight can make a big difference to that size motor/boat combo in my humble opinion..

 

[tashasdaddy]

Re: Hydrofoils

is the engine the correct shaft length for the boat.

 

[eatropefish]

Re: Hydrofoils

I've had the boat for a year. The motor is not the original. It seems to be the correct length because the cavitation plate is parallel to the bottom of the boat, if that is what you're getting at. The symptom is not new as I've been battling this issue since I took possession. When I say the prop breaks loose, I can feel it "grab" suddenly as I slow. When I'm by myself the boat goes pretty good. As far as weight goes, I don't know. 3 batteries(two for the trolling mtr) 6 gal gas tank. I keep the livewell empty. I think the motor is running well enough to "launch". I do have a new prop on the way just because I don't know the integrity of the OEM. Thanks for your input.

 

[eatropefish]

Re: Hydrofoils

And then again, installing a hydrofoil on a motor with prop issues won't accomplish a thing. Looking at what a hydrofoil does, it will probably make the prop tend to break loose easier with the increased water available at the prop. One other fact: The livewell In/out holes are directly in line with the lower unit.

 

[Silvertip]

Re: Hydrofoils

If you check the prop as I suggested you may find you do not need a new prop.

 

[eatropefish]

Re: Hydrofoils

If you check the prop as I suggested you may find you do not need a new prop.

Roger that. I'll feel better knowing I have a known good prop anyway. When I remove the old prop, I should see "witness marks" where the prop has moved on the hub, correct? Also, can the prop lose its rake(correct term?) or cup over the years? i.e. lose its ability to grab and move water. The engine doesn't seem to rev it just seems to churn the water rather than push.

 

[eatropefish]

Re: Hydrofoils

Update: Silvertip, I removed the prop and looked for any sign that it had slipped on the hub without success. I scribed a mark on the hub and prop and reinstalled. While waiting for time to go to the lake my hydrofoil came and I installed it. Made it to the lake(finally) and gave the boat a good performance test. I felt that my plane-out time was significantly decreased and the hole shot (if you can call it that) was better. Yesterday the prop I ordered came and I compared it to the old one. The new prop has a noticeable cup whereas the old one has none, almost straight or even flared. I think I've got this problem licked. The true test will be when I add another person. If you're interested I'll give you the results when I can get to the lake.