Lost 8-10 mph on top end on my Southbay

[newarkboater]

Guys and Gals

I have a 2012 Southbay 223 Sport-toonwith a 115 Yamaha . When I got it last summer I was toping out at around 28-30mph depending on the top being up or down and the lake conditions.

As of last weekend I was topping out at about 21mph (been in that range most of the summer as well), we have had a pretty windy summer so I attributed it to additional drag and choppy water. But was talking to someone and they said that should not cause that much decrease on an engine that new.

The boat sits in a unlifted covered slip. The pontoons have never been cleaned and have a but of goopy slime on them and the their is some slime on the prop as well, although i trying to wipe it off regularly.

Would that slime on the the toons and prop cause that much difference?

Thanks.

 

[Fleetwin]

Re: Lost 8-10 mph on top end on my Southbay

Guys and Gals

Would that slime on the the toons and prop cause that much difference?

Thanks.

Absolutely.

 

[wgl333]

Re: Lost 8-10 mph on top end on my Southbay

Top end MPH is one thing....have you tracked the RPMs? What range are they in now compared to last year when you were topping out at 30 MPH?

 

[Fleetwin]

Re: Lost 8-10 mph on top end on my Southbay

Top end MPH is one thing....have you tracked the RPMs? What range are they in now compared to last year when you were topping out at 30 MPH?

Good point. Nowever, if the prop is fouled, you may not get top RPM either.

If you are going to clean it, a pressure washer works well. Make sure to clean it while it's still wet. That slime can harden in to some pretty rock hard stuff.

 

[newarkboater]

Re: Lost 8-10 mph on top end on my Southbay

Good point. Nowever, if the prop is fouled, you may not get top RPM either.

If you are going to clean it, a pressure washer works well. Make sure to clean it while it's still wet. That slime can harden in to some pretty rock hard stuff.

RPM?s are running about the same as they did last year. Maxes out around 8000 (which may actually be 9000 due to the fact that when sitting still and turned off, the RPMS are on 1000)

I don?t have a trailer or a lift, so I am not sure the best way to clean them off. Any suggestions?

I am amazed that slime and gunk would effect the performance that much.

Any treatments that can be done to lessen the growth or do I need to bite the bullet and put it on a lift?

 

[lakegeorge]

Re: Lost 8-10 mph on top end on my Southbay

You need a stiff scrub brush and get in the water and clean the logs. There is probably a lot more crud on them that what you think. Dirty logs will definitely cause you to lose speed.

You may need to check and make sure that you don't have water in the logs also. I assume that your speed is by GPS?

 

[Water logged]

Re: Lost 8-10 mph on top end on my Southbay

8 or 9000 RPM seems a tad high on that Yamaha. Are you sure of those numbers, I don't know much about Yamahas, but that just don't sound right. I've had people tell me that the 6400 red line on my Merc is excessive.

Glenn

 

[newarkboater]

Re: Lost 8-10 mph on top end on my Southbay

You need a stiff scrub brush and get in the water and clean the logs. There is probably a lot more crud on them that what you think. Dirty logs will definitely cause you to lose speed.

You may need to check and make sure that you don't have water in the logs also. I assume that your speed is by GPS?

Yes speed is by GPS

 

[newarkboater]

Re: Lost 8-10 mph on top end on my Southbay

Glenn

I may be off on the Rpm's i am trying to remember what the numbering is on the tach and assumed it ran 1-10.

It may be running between 5-6 ( and the more I think about it I think about it I think the tach runs 1-8 which would put be running between 5-6).

I will check the dial this weekend and make sure I have the right rpm numbers.

The needle is generally in the same place as it was last year at full throttle.

The odd thing us there is no red line on the tach.

 

[MaPaHa]

Re: Lost 8-10 mph on top end on my Southbay

I had pretty good luck with some course scotch brite pads when mine was off the trailer and on blocks but it was dry and crusty. I think I would have rather done it in the water. I would take advantage of the remaining warm weather and get a handful of pads and some help with good arms that want to get in the water. Just take a crew out to an island and then tell them what it takes to get back:laugh:

 

[Water logged]

Re: Lost 8-10 mph on top end on my Southbay

Glenn

I may be off on the Rpm's i am trying to remember what the numbering is on the tach and assumed it ran 1-10.

It may be running between 5-6 ( and the more I think about it I think about it I think the tach runs 1-8 which would put be running between 5-6).

I will check the dial this weekend and make sure I have the right rpm numbers.

The needle is generally in the same place as it was last year at full throttle.

The odd thing us there is no red line on the tach.

Also no redline on the tach, but there is a tag on the motor stating 6400 max rpm.

Glenn

 

[bldtrailer]

Re: Lost 8-10 mph on top end on my Southbay

I cleaned my toons a couple of weeks ago and gained 7 mph. I use a plastic paint scraper and it works well, just takes a little time.

 

[The Woo Woo Kid]

Re: Lost 8-10 mph on top end on my Southbay

I worked at a marina one spring. We launched a 25 ftish vhull that a large I/O motor and a dual propeller(twin screws) drive. The motor had been gone over by the mechanics, tuned....everything fine. The hull was cleaned and waxed. Once in the water, it would not gain speed at all or get up on plane at all. It would just go slow, plowing through the water at slow speed and the engine was hitting max rpms.

What the heck, right ?

So we pulled it out of the water. Lo and behold, there was a piece of tape sticking to one of the props, left there from the shrink wrapping. It was only about an inch wide and 5-6 inches long.

Pulled the tape off and the boat ran great.

 

[Bamaman1]

Re: Lost 8-10 mph on top end on my Southbay

Yamaha engines have rev limiters that cut out at about 6300 rpm's. And yes, algae on the toons will slow you down that much.

If you're going to keep your boat in a marina, first stop is a beach or sand bar where everyone on the trip is assigned their own ScotchBrite pad for a mass cleaning.

If you're going to invest so much in a pontoon boat, you need to protect your investment. I believe in either having all boats on a lift out of the water, on a trailer or in a marina in a warehouse storage--out of the water.

I still have a 1985 Starcraft pontoon without a scratch or dent. Pontoons and tritoons have a long, long (over 30 year) lifespan if you keep them dry and out of the weather.

 

[WaterDR]

Re: Lost 8-10 mph on top end on my Southbay

Mine stays in the water and I clean the toons about every week to two weeks. I have a brissle brush on a long poll and use pads. Works great. If you stay on top of it, it only takes a few minutes.

 

[newarkboater]

Re: Lost 8-10 mph on top end on my Southbay

thanks guys, I cleaned the prop and motor and part of the toons this weekend, hope to finish it up next week, seems to be running faster