Getting on plane question

[choppywaters]

When we take more than myself, wife, son and daughter out our boat does everything Smart Tabs says will fix. It bounces all the time, (Ive tried adjusting the trim over and over), it takes forever to come up on plane then when it does it seems to take off. This weekend there were our usual 4 and 2 others,(with coolers about 900lbs max), we went tubing and even with the trim all the way down we still couldn't get on plane unless I had it at wot but with a 6yr old in the tube I wanted to go maybe 10ish mph. I realize our boat isn't some powerhouse but with a 4.3LX motor I would think it would do better than that. Any ways I called a marine dealer to see if he had these Smart Tabs and I explained to him whats going on and he said its a prop pitch issue. I have 2 props, the one thats on it now is a 19 pitch 3 blade and the other is a brand new 21 pitch. He said try a 17 pitch prop but even that might not make a difference with the typical load I had on. Any thoughts?

 

[Philster]

Re: Getting on plane question

Your Stingray hull is a classic, time-honored 'porpoiser'. You need tabs to fix that. Smart Tabs would be great.

Now the performance. You need to run the boat with an typical load and run it to top speed and record the engine RPM. Then get back to us.

In lieu of that semi-critical info, a boat that has a family on it and is tubing, unless it's overpowered, is probably going to need a better/smaller prop.

So, now we need to know what kind of prop (aside from just blade count) you have now. Make, material, model, etc.

It's still safe for me to say that you should spin a 17p prop, with weight distributed properly on the boat fore and aft with some tabs to enjoy watersports with the family.

You're killing your engine right now.

 

[Scott Danforth]

Re: Getting on plane question

I agree, you may need to drop down to a 17p prop. did you move some weight forward? when I tubed or skied behind my Avanti, I had to move everyone to the bow and run a 17p prop in order to get any type of hole shot. your 597 is a small cuddy, so you cant easily just walk to the bow

at 900#, you may be near the max the boat is rated for.

 

[markheck1]

Re: Getting on plane question

Yeah, your boat is a foot longer bout 100 pounds heavier and 23HP less than mine, and I find that a 17 works pretty well on mine for most things, If I was gonna be in Erie any time soon I'd let ya try one.

I found an old old set of small spring loaded tabs that seemed to help a lot more than that silly whale tail did. I want to get some bigger better ones, I think they will help even more.....

You should still get all the info in the sticky before changing just to make sure,

 

[Texasmark]

Re: Getting on plane question

All good info and I agree.

Additionally, you clearly described too much pitch in your prop. First off, you are loading your engine in your sloppy hole shot you mentioned, continuing on with a water toy drag...making a bad situation worse, and not allowing it to develop it's rpm's. Since rpms are 1/3 the definition of HP, you aint-a developing your hp so you cannot expect the performance your hp rated engine is supposed to develop.

Secondly, you are "seconding the motion" when you described your taking off. Once on plane you reduce the drag of the boat, hence unloading your prop, hence allowing your engine to get up to it's rated rpms, or in that direction anyway, and that is why it takes off.

The third thing you didn't mention but you probably noticed was that as you reduce speed, from higher rpms to say cruising speed, or just above plane out speed the boat wants to sink in the water, you increase the throttle to get it back up, the unload process kicks in again, then you are going too fast for where you want to operate so you cut the throttle back, dog chasing his tail!!!!

If 17 doesn't fix it, then you may have to go to a 15. Once you get her right, these symptoms should disappear and you should enjoy your boat as you expect............get the numbers like Philster said.

HTH,
Mark

 

[nlain]

Re: Getting on plane question

I went to the Stingray site and looked up your boat. Boat weight less engine, 1760 lbs., engine drive package, 802 lbs = 2562 lbs. dry weight approx. 4.3LX engine should be 205 HP @ crank or 175 @ prop. Standard prop should have been Alum, Quicksilver 13 3/4 x 21 or optional SS Turbos1 14 1/4 x 22. Max Cap: Persons/lbs 8/1600. Just some info to put in when op get more info on performance and boat.

 

[Captain Caveman]

Re: Getting on plane question

Yup - all great points. I'll just sum it up. You're over-using your boat. You can make some changes as all stated above but your boat wasn't made for what you're trying to put it through. If it were, you wouldn't be asking these questions.

 

[JimS123]

Re: Getting on plane question

I went to the Stingray site and looked up your boat. Boat weight less engine, 1760 lbs., engine drive package, 802 lbs = 2562 lbs. dry weight approx. 4.3LX engine should be 205 HP @ crank or 175 @ prop. Standard prop should have been Alum, Quicksilver 13 3/4 x 21 or optional SS Turbos1 14 1/4 x 22. Max Cap: Persons/lbs 8/1600. Just some info to put in when op get more info on performance and boat.

The Stingray people market their boats on performance......or should I say speed! Their charts are based on a light load and 2 people - ane even then its very conservative. Their prop recommendations are wrong for 90% of the applications. You need way less pitch than what's listed.

A $20 home made tab (like they now offer as an option - look at their catalog) will fix the porpoising problem. The right prop pitch will fix the rest.

 

[Philster]

Re: Getting on plane question

^what he said

My boat came propped for one nut job, 1/4 tank of fuel and a desire to chine walk on a calm lake for the last 2-3 MPH so you can say, "Yeah, she does 72." I'm not a complete nut job, don't boat on lakes and don't like chine walking at 72 with a bow that feels like it's a kite.

Um.. well, I tasted that, and I think she's better as a 65-68 MPH boat without a chine walk and a prop that lets me carry an actual family and do some skiing and tubing.

 

[Texasmark]

Re: Getting on plane question

^what he said

My boat came propped for one nut job, 1/4 tank of fuel and a desire to chine walk on a calm lake for the last 2-3 MPH so you can say, "Yeah, she does 72." I'm not a complete nut job, don't boat on lakes and don't like chine walking at 72 with a bow that feels like it's a kite.

Um.. well, I tasted that, and I think she's better as a 65-68 MPH boat without a chine walk and a prop that lets me carry an actual family and do some skiing and tubing.

Hey Chine my man, not being pessimistic, but not understanding your comment, what sir did this display of performance specifications of one of your water toys have to do with the subject matter, sir.

Mark

 

[Philster]

Re: Getting on plane question

Some makers put a prop on that works with just about no load but fails to deliver with an actual family on board.

Read the OP.

It's relevant: If your stock prop ain't delivering the goods, then it's normal to have to replace it to use your boat in the real world.
.

 

[choppywaters]

Re: Getting on plane question

Great advise and info guys.....thanks! I will get some more info asap. If I remember right I did look at the rpm's at wot with the load I stated before and it was 4300ish and the speedo read 35ish mph.

 

[choppywaters]

Re: Getting on plane question

Hi again guys, I have some additional info. The prop that is on it now is 14 1/4 19p and silver in color (I would assume a Quicksilver) there are no other visible numbers or markings on it anywhere I could see. Again when I happen to look down at one point we were pretty much at wot and it was between 4300-4500rmp's and we were running about 35-40mph.

 

[dockwrecker]

Re: Getting on plane question

I'd do the Smart tabs regardless, but yes you appear to be over propped. The combination of the tabs and at least stepping down to a 15/17 would make a world of difference. A 15/15 may be the ticket especially if you're running at any kind of altitude above 3500 ft.

 

[choppywaters]

Re: Getting on plane question

I'd do the Smart tabs regardless, but yes you appear to be over propped. The combination of the tabs and at least stepping down to a 15/17 would make a world of difference. A 15/15 may be the ticket especially if you're running at any kind of altitude above 3500 ft.

Do you think a 15p prop would be too much? I don't care about top speed, most of the time well be cruising or towing a tube.

 

[BonairII]

Re: Getting on plane question

I would choose the 15(assuming it won't run your rpm past max). The lower pitch will make your motor happier, boat jump on plane easier....and help you stay on plane at lower speeds.

Run the 15p prop for tubing and when you are heavily loaded. And use a 17 or 19 when you are lightly loaded and want some more speed.

 

[choppywaters]

Re: Getting on plane question

I would choose the 15(assuming it won't run your rpm past max). The lower pitch will make your motor happier, boat jump on plane easier....and help you stay on plane at lower speeds.

Run the 15p prop for tubing and when you are heavily loaded. And use a 17 or 19 when you are lightly loaded and want some more speed.

I think I might just do that. The 15p will possibly push the 5000rpm range but 99% of the time we're just cruising and no where near wot. Ordering my Smart tabs tomorrow.

 

[dockwrecker]

Re: Getting on plane question

Do you think a 15p prop would be too much? I don't care about top speed, most of the time well be cruising or towing a tube.

Maybe find out if your local boat shop "rents" props? Mine does to see if they work for your situation.

 

[BonairII]

Re: Getting on plane question

I think I might just do that. The 15p will possibly push the 5000rpm range

If you're motor's max rpm rating is 5000rpm....going over by a couple hundred rpm ain't no big deal at all. If it worries you, just run it to 5k.

 

[fishrdan]

Re: Getting on plane question

Carrying a heavy load and doing watersports, a 4 blade prop would work better that a 3 blade. At 4300-4500 the WOT is low, so you'll need to drop pitch more than the recommended -1 inch when going to a 4 blade prop. I'd think a 17P 4 blade should work, maybe a 16P if the WOT is actually closer to 4300RPM.