Slow to Plane

[nhmtnlaker]

New to boating have 87 chapparral 195 / 200hp. Boat is slow to plane, especially with load. I have 21 pitch prop, should I change?

 

[QC]

Re: Slow to Plane

Welcome to iboats nhmtnlaker!!

Well first we'll need some more info to help.

1) Do you know what the RPM is at wide open throttle? Need to know what RPM the engine is at when operating as fast as she will go with an average load and trimmed properly. Check here for more info:

FAQ WOT thread

2) 200hp what? I/O? Make model year all the stuff

3) Have you ran a boat before? Define long time to plane, more than 10 seconds?

4) Where do you boat? Altitude?

5) Do you know any history of this boat?

Basically we need to know if it is running correctly now and some other specifics before we can determine if it is right as is or needs some help.

 

[waterinthefuel]

Re: Slow to Plane

What QC said.

 

[vacayooper]

Re: Slow to Plane

Make sure the boat is loaded correctly, the engine is tuned up and the filters and fuel are fresh. I made the mistake of easing up on the maintenance of my boat and had a miserable time looking up at the sky while starting out. A new fuel filter, cap, rotor and serviceable battery later that problem is gone. There are plenty of 4 cylinder boats out there performing just fine but you have to take it for what it is. If you are boating up at a high altitude you generally loose 20 % of your performance, going numerically lower on the prop helps out but make sure you stay in your engines rpm range.

 

[Jdeagro]

Re: Slow to Plane

assuming everything else is OK, changing the prop to a lower pitch will help, but it will be the same as driving your car in low gear all the time. At todays fuel cost I do not think this is a good deal.

Look at Trim Tabs first.

 

[QC]

Re: Slow to Plane

Make sure the boat is loaded correctly, the engine is tuned up and the filters and fuel are fresh. I made the mistake of easing up on the maintenance of my boat and had a miserable time looking up at the sky while starting out. A new fuel filter, cap, rotor and serviceable battery later that problem is gone. There are plenty of 4 cylinder boats out there performing just fine but you have to take it for what it is. If you are boating up at a high altitude you generally loose 20 % of your performance, going numerically lower on the prop helps out but make sure you stay in your engines rpm range.

These are potentially valid comments, but we need to help him focus instead of throwing parts at it before we even know if there is an issue. Also, just for clarity, if it is indeed a 200 (whatever that is) this is not a 4 cyl. I would be very surprised if there was a 4 in a Chap 195 anyway . . .

 

[nhmtnlaker]

Re: Slow to Plane

Boat is a 87 chapparral 195 xlc bowrider with 200 hp / v8 mercruiser / alpa 1 I/O. I bought it used in aug 2005, my 1st boat.

I see a comment about altitude, 1350' is where lake is.

I haven't tuned up boat but cleaned air filter and was have been running 89 octane fuel was thinking of trying 93

 

[nhmtnlaker]

Re: Slow to Plane

Welcome to iboats nhmtnlaker!!

Well first we'll need some more info to help.

1) Do you know what the RPM is at wide open throttle? Need to know what RPM the engine is at when operating as fast as she will go with an average load and trimmed properly. Check here for more info:

FAQ WOT thread

2) 200hp what? I/O? Make model year all the stuff

3) Have you ran a boat before? Define long time to plane, more than 10 seconds?

4) Where do you boat? Altitude?

5) Do you know any history of this boat?

Basically we need to know if it is running correctly now and some other specifics before we can determine if it is right as is or needs some help.

 

[QC]

Re: Slow to Plane

OK altitude does not seem to be an issue. Octane is not the issue either unless she is knocking (pinging) which you should be able to hear.

We really need to know your RPM at WOT, trimmed for the fastest speed possible. You may indeed have a problem, but we need to know this other stuff first. Try rereading my list and give us everything you can. It may need all kinds of work, it may simply need a prop change, but we need to start with info.

 

[nhmtnlaker]

Re: Slow to Plane

-Boat planes at just over 3000 RPM and I haven't exceeded 3500 or so, at least by gauge reading. That is with throttle fully forward
-Takes over 10 seconds to plane. In some cases, with say 6 people, it may not plane.
- trim in all cases is with outdrive in fully down position
- I haven't heard pinging as you descibed, so that is probably not it. it sounds pretty smooth when running on plane, at ~35 mph
-Boat is a 1987 chapparral 195 xlc bowrider with 200 hp / v8 mercruiser / alpa 1 I/O. I bought it used in aug 2005, my 1st boat. I'm new to boating,
- I bought new prop, this year as the one that came with it got dinged. It is a 3 blade 21"
- Boat has been sitting. Previous owner took it in trade when he owned a marina, probably has been sitting for a few years. He cleaned it up before selling it though.

 

[QC]

Re: Slow to Plane

OK, now we're getting somewhere. The WOT RPM is definitely too low as it should run much higher RPM if it is right. If the tach is reading correctly (need to verify) and she is running right, then your propeller pitch is too high as is. First thing is you note 3500 RPM. You also say that "I haven't exceeded", I assume that you tried to exceed that RPM and she wouldn't do it, right? After she planes try raising the trim a little tiny bit at a time and see if that gains you some speed and RPM. As you are trying higher and higher trim, if you start to get more RPM and no increased speed then trim back down slightly; you have probably found the max trim setting for that speed, hull and prop combo. I do, however, believe from what you say she has some other issues too.

Even with six people and the 21 inch prop, I think she sounds sluggish for a V8. She should pull a 19 inch prop if everything is right, but that won't account for 1000 RPM which is how far off you are. I believe that power package is rated for 4200 - 4600 RPM.

1) Verify the tach is right
2) See what RPM you can get at WOT with the boat empty and using the trim up some (follow directions in notes in previous paragraph).
3) You probably still need a complete tune-up and filters etc, so do that and verify numbers again (best to have both sets of numbers, before and after tune-up, to get as much info as possible)
4) Prop to allow around 4600 or so with an average load (200 more RPM for each inch less in pitch) after she is running right. You can keep the 21 as a spare as you really need one on board anyway . . .

Good luck!! This sounds like a lot, but is a pretty typical deal . . .

 

[studlymandingo]

Re: Slow to Plane

Wow! if 35K is WOT, then there are definitely some issues. Definitely start with the tune-up as suggested, a V-8 should be shooting that thing out of the water.

Check for waterlogged foam or water trapped in the hull. Beyond that, you are probably going to need a prop change, however to get 1000 more rpm, you'll technically have to go down to a 15p which is WAY overkill for the V-8.

 

[tashasdaddy]

Re: Slow to Plane

the easiest way to tell if you are carrying extra weight is to go to a public scale, and have the boat & trailer weighted. NADA says you boats dry weight is 2400lbs, you can go to NADA and find your trailer weight. compensate for gas at about 6lbs per gallon. usually a charge of $10.00.

 

[Texasmark]

Re: Slow to Plane

Other thing he said was that he was trimmed in all the way. Didn't say if he trims out when he gets on plane.

If he doesn't he may be "plowing" which will surely bite into his rpm's and speed.

Just whipped out a '97 Mercruiser catalog. No 200 hp V8's in it; V6 yes.

On the 5.7 litre V8 WOT Max is 4600 rpm's so the comment about being 1000 rpm's low is right on.

The Alpha 1 comes in 1.47 all the way to 2.4 so it would help tremendously to know this in trying to understand if the prop is right.

If he is running the standard gearbox, gears are 1.62:1. So swinging a 21" prop at 4600 rpm with 15% slip (big load) should give him 48 mph. 20% of slip and he is at 45 mph.

Assuming he is overpropped or plowing, I'll run the slip to 20 and the rpm's to 3500 and we have 34 mph which pretty much agrees with his WOT mentioned numbers.

Interesting note: He said he planes out around 3000 but WOT is 3500 :%

He ought to scoot once he gets out of the hole.

Gotta be plowing

Trim her out New Hampshire Mountain Laker and get back with us.

Mark

 

[nhmtnlaker]

Re: Slow to Plane

Thanks for the inputs. Tryed using 93 octane gas, seemed to get some boost there, didn't notice pinging prior to that though. maybe this still points to need a tune up. Ordered a 19" pitch prop, will try this weekend. Measured WOT was just under 4000 rpm, on plane at 35 mph. Needs to be over 3000 rpm to plane.

I run prop at full down angle, no other trim settings, both from start and running.

Need to put most of people weight in bow to plane in less than 15 seconds though

 

[tommays]

Re: Slow to Plane

You will never reach the correct WOT without triming up the drive after you get on plane

The 19" will get you there faster BUT will still require useing the trim to get good performance out of the boat


Tommays

 

[nhmtnlaker]

Re: Slow to Plane

Changed to a 19" prop this weekend, much better acceleration. Full throttle got it to plane in a few seconds instead of > 10 that I was experiencing. The RPM settled out at ~4500 with this prop at ~38 mph. Not sure what my 1987 Merc / alpha 1 (V8/200 hp) should hit. Will address tune up next. Thanks for the inputs.