The boat I use is a 21 ft SunTracker Party Deck with a Mercury 150 outboard (1998).

This picture is from Tracker's web site just so you can see exactly what the boat looks like:



If I go half to full throttle I get soaked by the spray that is coming off the sides. This means that I need to go really slow everywhere even when I have a long ways to travel accross the lake.

I really don't think the boat is planing out correctly. Can you offer any advice? There is a hydrofoil plate installed and I was thinking about taking it off to see if that helps any.

[This message has been edited by Duck_Man (edited 11-13-2003).]

I'm assuming you are trimming the motor up after you get on plane? That will raise the bow some. Don't know how much on a deck boat though. Have you asked the guys over at BPS in Katy?

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I try to trim it up once I get going but for some reason it doesn't stay. I was wondering if the hydrofoil was maybe pulling the motor back down and not allowing it to stay trimmed?

It never really seems to come out of the water very much so it throws a lot of water.

If it's not holding trim, you may have a T/T hydraulic problem. If you run with full down trim then you will have a lot of spray.

When you take off & get on plane with WOT, you should trim to maximum rated RPM. That's running WOT. If you're running at lower power settings then your trim will be slightly different. It's kind of an acquired feel or talent. I always come out of the hole with full throttle and start trimming out. Then I'll come back on power to the desired spot then make minor adjustments to the trim to minimise prop slippage.

I don't have any experience driving a deck boat, but it should be too much different than driving a bass boat.

Well, I am going to take it out tomorrow night. I try to do what you're saying but the trim doesn't hold. I think I will take the hydrofoil (trim plate) off tomorrow and see if that reduces the presure on the motor so it can hold the trim.

I think the biggest difference between this boat and a bass boat is the weight, this is a very heavy boat.

Thank you very much for your input. I'll also try what you said about trimming out to max rated RPM. So I just trim out until the RMP's are maxed and I am not getting prop slippage, right?

Can you recomend a way to check the hydrolics for the T&T ? Is is possible for it to just get low on hydrolic fluid? If so, where could I check the level and add fluid?

About the only time you'll run into major slippage is if you're trimmed too high for the power setting. Between watching the tach and speedo or feeling what the boat is doing you can pretty well tell when you 're slipping. Your RPM will go up but no increase in speed or you may actually slow down. From there, if you trim back down a little, then you'll feel the prop grab and the RPM will take a pretty good drop. One of those things you can get out and play with and get the feel for. for running wide open, you just trip until there's no speed increase (then just a touch of down) or you reach max rated RPM.

Can't picture a Merc 150 T/T right off, but there should be a reservoir on the tilt & trim mechanism with a cap screw plug in the top. You can check your level there. Should be just to the running out point. Top it off with tilt & trim fluid from your dealer. Screw the cap back on and run it up and down a few times then repeat. This bleeds the system. If you're losing fluid, you should see evidence back there somewhere.

Just thought, with the motor full down, look for a hole in the right side of the bracket. There should be a large slotted screw head in that hole. That's the bleed valve. With the PROPER SIZE screwdriver, make sure it's all the way in and snug. If not it will bleed pressure off.

There are also internal valves that can be defective. If that's the case then it's get out the wallet time!

Good Luck!


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A friend of mine has the exact boat and year. His has a 120 Force on it. I know it is underpowered but it does pull me up slalom, slowly but it does have enough power for that. When he is running WOT, and the lake has a little chop, we get wet. First thing I would do if I were you, would be take the hydrofoil off. What kind is it anyway? The reason I ask is that a Doelfin has a downward hook to it and if the motor is not mounted high enough on the transom it will fight against your trim and that will not allow you to maximize your trim range. Try it then. Have you ever had the prop worked on? You probably do not have enough cup in it. Ask the guys at B & B prop what is the worst thing about a factory Mercury prop. I had the same problem (not enough bow lift) with a 1998 Mercury 200hp on a 20' ProCraft and they put more cup in it and after that I could get damned near all the boat out of the water. My friend that has the same boat has not taken the time to have his re-worked. I just don't think he wants to spend the money on it, LOL. He is still kicking hisself in the rear for not getting the 150 but it was going to cost him about $4000 more. His motor will only go up to 5000rpm's and I think that is about tops for a Force. You ought to be able to spin that Mercury up to 5600-5800 rpm's.

Duck-man,

Your boat is very similar to my last boat. You have to get the bow up on a deck boat when on plane in order to stay dry if there is any chop. You just need to figure out why your motor is not staying trimmed out, that will fix your problem.

As for how much trim, on my old deck boat if there was much chop at all the boat would start to porpose as I added trim way before I maxed out the RPMs. I could trim higher (and go 5-7 mph faster) on calmer water.

Joe

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jsteve,
that's some excellent feedback. I don't know what brand the hydrofoil on the motor is, but I am going to take it off tonight to see if that helps. I did have the prop worked on about 3 months ago after I bent it on a log, and when I got it back it had better cups on the tips than when I took it in there. I noticed a significant improvement in performance, but I still get wet, hopefully the hydrofoil removal will help the trim problem.

Part of the reason I thought about taking it off is that I read on this forum somewhere that the fin should be above the water when the boat gets to plane, and mine does not, it stays under the water.

Capnjoe,
Is porposing the same thing as prop spippage? I notice the exact same behavior on this boat.

I am really going to pay attention to the RPM/trim behavior tonight.

Porpising is the front end of the boat
bouncing up and down. All boats will spray
water when running fast, if the wind is
blowing very hard it always blows the spray
on someone in the boat If you are taking the
spray on a calm day then you have a problem
Getting wet is part of the game, I think.
Just keep on fishin'

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Dennis

Thanks for explaining that. The boat doesn't porpose then, it just gets prop slippage. I've been in quite a few boats and this one is definitely worse that the others. A little spray doesn't bother me, but driving through a wall of water is another thing! Especially wen it's cold out!

When it is hot I think it's a nice feature, unless my beer gets too watered down!!

j.steve,
I had a doelfin on my last boat. When I went to buy it, I was actually going to buy a Sting Ray, but didn't because of the downward hook it had on the trailing edge. I bought the Doelfin because it didn't hvae the downward hook...it just looks like an airplane wing. Are we talking about the same thing or is there something I missed?

Duck_Man,
It sounds like your trim unit is losing pressure, causing the motor not to stay trimmed up under power and the fin is making the problem worse by forcing the nose of the boat down even farther (doing exactly what it's designed to do).

Removing the fin may help the spray problem, but I'm guessing that it won't help the trim problem.

By the way, my Doelfin never came out of the water...when it did (rough lake or too tight turn) the boat got squirrely.

Thanks maddog duck, I am going to take it off tonight and see if that helps the trim problem. My guess is that your right and that I will also need to check the trim mechanism as txchamp recommended.

I'll post before monday with what the result was.

Could be that the prop pitch is too high, not getting enough bite on the water, allowing the prop to slip, and when it slips there goes your bow lift.....

Maybe try a lower pitch prop.....