Stabilizer tail/fin options for 98 Stingray 19' with a Merc 3.0

[jkimball]

Re: Stabilizer tail/fin options for 98 Stingray 19' with a Merc 3.0

I DON'T like engine or drive mounted fins. They are more trouble than what they fix. A Band Aid.

Smart Tabs or Bennet Trim Tabs are the best solution.

They are not a Band Aid. Many new boats are built with trim tabs.

I don't have anything specifically against foils.
They work for some boats, and don't work for some. It really is just depending on the boat. Like I said, I had one on it, and I liked it when I first got it because it really seemed to plant the nose out of the hole, but it also seemed to do this throughout all trim settings.
I tried it, and then I tried other things, such as a prop. I ultimatley found that changing the prop really was the cure for my problems.
Again, I don't hate them, they have their place. But I also think that for the $$ you spend, you can probably correct the actual problem.

 

[NYBo]

Re: Stabilizer tail/fin options for 98 Stingray 19' with a Merc 3.0

I DON'T like engine or drive mounted fins. They are more trouble than what they fix. A Band Aid.

Smart Tabs or Bennet Trim Tabs are the best solution.

They are not a Band Aid. Many new boats are built with trim tabs.

While trim tabs are probably the better solution, if the hydrofoil fixes the problem, it's no more of a band-aid than trim tabs are.

 

[achris]

Re: Stabilizer tail/fin options for 98 Stingray 19' with a Merc 3.0

...If I understand it correctly, this is what is referred to as slip. The actual pitch that a propeller produces vs. the theoretical pitch it should produce. ....

Not quite. You have slip and pitch the wrong way 'round.

The pitch of the propeller (measured in inches) is the theoretical distance the propeller will move forward in one completely revolution.
Slip (measured in percentage) is the difference between the theoretical distance and the actual distance in operation.

Example. I'm running a 17" pitch propeller at 5000rpm and getting 38 knots. Gear ratio is 1.62:1

Theoretical speed (speed is merely distance traveled over time)
17" times 5000 divided by 1.62 times 60 (minutes in an hour) divided by 72240 (inches in a nautical mile).

17*5000/1.62*60/72240=43.6 (knots)

Slip = (theoretical speed minus actual speed) divided by theoretical speed times 100 .

(43.6-38)/43.6*100=12.8%

Chris.......

 

[mphsjeep]

Re: Stabilizer tail/fin options for 98 Stingray 19' with a Merc 3.0

.......ouch......math :joyous:

 

[crabby captain john]

Re: Stabilizer tail/fin options for 98 Stingray 19' with a Merc 3.0

Prop change would be great if it works and very well might. You do a lot of high speed running with varying loads and people moving around-- be smart and get real tabs from Lenco or Bennett

 

[achris]

Re: Stabilizer tail/fin options for 98 Stingray 19' with a Merc 3.0

Now that you mention....there is another prop that came with the boat. I think he said it would give more top end but less pull power. What's the rule of thumb with prop sizes?

Yes. Use the prop that allows the engine to run at the manufacturers' recommended WOT (Wide Open Throttle) rev range.

Your engine has a WOT range of 4400-4800. So put a propeller on and take it for a run. Open it right up and see what your engine speed is (ideally should be done with a calibrated tacho). If it's in the 4400-4800 range, great (hopefully it's towards the top end of that). Now, when you go tubing or skiing, ect change the prop to one 2" in pitch SMALLER. That will reduce the load on the engine, which has increased because of the tow-sport, and allow the engine to rev quicker. You'll notice the boat will feel more 'driveable' too... I have a prop on my boat that would allow the engine to run to about 5200 if the rev limiter didn't stop it. But I like it, it's better for the engine, and despite what 'people' will tell you does not use any more fuel (I have a 19" prop too and have done the trials) and the boat gets up out of the hole like a scolded cat! It won't harm the engine, and the engine iwll love you for it. Less wear (also on the drive) and better throttle response... Unless you are 'balls to the wall' all the time, I'm yet to see a disadvantage... (I've been running boats like that since 1983)....

Chris.....

 

[mphsjeep]

Re: Stabilizer tail/fin options for 98 Stingray 19' with a Merc 3.0

Thanks!!!!! Did not have a chance to look at the prop sizes I have but will tomorrow and report back.

 

[gtochris]

Re: Stabilizer tail/fin options for 98 Stingray 19' with a Merc 3.0

What size 4 blade do you have?

It's hard since it has been black spray painted so many times... I "think" it's 19 pitch... I have a next size lower one and it doesnt make a sizable enough change in towing torque but severely hurt the top end.

With the 4 Blad I have now, I'm around 5K RPM's at Wide open and 39-40 MPH.

 

[mphsjeep]

Re: Stabilizer tail/fin options for 98 Stingray 19' with a Merc 3.0

Ok...I think I have a 19 pitch on the boat and a 21 pitch to try out. I could barely read the punched painted over numbers on the side but here they are plus the numbers inside the hub:

On the boat:
48 832830 19 01(in hub) 48 832830 415 19P(on side)
To try:
48 832832 C1 21(in hub) 48 832832 415 21P(on side)

Do all these numbers have any meaning? Is the diameter on these 15"?

Chris, going by your post above and what I remember the prior owner telling me I think my guess is right. Do these sound like the correct pitched props for my boat/engine? And clarifying, will the "more driveable" feel come from the 19 or 21 pitched prop?

 

[achris]

Re: Stabilizer tail/fin options for 98 Stingray 19' with a Merc 3.0

The first parts of the number on the props are their Merc part number (48-832832 41A), the last is the pitch, 21"...

The 19" will accelerate quicker and the throttle will be more responsive, but the engine will rev a little high for any given boat speed. You just need to put the props on and take them for a test run... Remember that with your engine, you're looking for a full throttle engine speed of 4400-4800. (Personally a hundred or 2 over wouldn't concern me).

Chris.....