1986 bayliner contessa top speed-gctid809169

[Jamesd1515]

Ive had this boat for one season. All winter went arround asking everyone who knew anything why my boat only goes 9 miles per hour gps. No one could tell me why but i know there is somthing wrong. It is a single prop volvo penta v8 with a b2 prop. Once i get to half throttle we reach top speed and rpms around 3100 the rest of the throttle sounds like it is working harder but makes absolutely no difference. Anyone have any ideas?

Thanks

[Download_Complete]

Ugh...

Okay, first, a single prop VP won't have X# props...they would be a standard diameter x pitch measurement.

Secondly, you provide no information on the service history of this boat. When was it tuned up last? When was the timing checked? Is the engine original? Is the bottom clean? Has the outdrive ever been replaced?

This boat should top out around 30 mph wide open, and cruise comfortably while on plane. You should see 4400 RPM wide open.

So yes, I would say you have significant problems. And there are literally a thousand variables between what you posted and your answer.

[360_mafia]

First check simple things.Get # off your prop.There are two web sites that will tell you if that prop works on your outdrive and engine.Google your boat make and length to see if they ever had your engine as a obtion.Get name and model of carburetor and make to insure it goes with your engine.If engine was rebuilt,there can be alot of issues like auto parts instead of marine parts .Last i remember a set up that used a rubber boot in place of a shear pin on props.Prop could be slipping on that boot.Other members will know better on that.keep us posted

[Download_Complete]

I can simplify this for him because when it comes to Bayliner, especially for 1986, I AM Google. Officially there was only 1 engine offered: a 5.7L 260 hp Volvo, which is sufficient for most boating locations, and adequate at best.

UNofficially, there were three more: twin 125 hp 4 cylinders, twin 5.0L 225 hps, and twin 5.7L 260s, which only got ordered at altitude out in Utah and the rest of the Rockies.

We need to know what engine it has, and the health of that engine. What he is describing could be fuel or timing related, or it could be something worse.

We also need to know where he is. A stock 260 that is getting tired will not plane the boat in Lake Powell, but it should be okay on the Atlantic.

[Jamesd1515]

I am on lake huron. To the best of my knowledge it is the 260 engine. And yes it does not plane what so ever.

[Jamesd1515]

The first thing i thought ithat was the prop was slipping. Would a new prop stop the slipping and therefore tell me that was the problem?

[Amadaies]

First we need to know what you have for sure. Pics will help tremendously! of the engine and outdrive.

You could have a slipping prop but doubtful.

Start with the basics. All cylinders getting good spark? Carburetor clean and functioning properly? What is the compression on each cylinder?

[Download_Complete]

"Jamesd1515" post=809195 wrote:
The first thing i thought ithat was the prop was slipping. Would a new prop stop the slipping and therefore tell me that was the problem?

This is easy - a slipping prop feels exactly like a slipping clutch in a manual transmission car. You apply throttle, thrust falls away, and the engine RPMs race. The more the hub slips, the lower the RPM this occurs at, until you basically have no thrust at all even at idle speed.

Thats not what seems to be happening here. So let's start simple - take some pics of the boat, the engine, and the drive if possible. If you have a quick video (30 seconds or less) while trying to get on plane, that helps too.

Barring all this, throw some money at it: Give it a compression test to determine engine health. Then do a full tuneup. Then check and set the timing.

If the engine is healthy, but still won't put power down after this, the carb is the next place to look.

[builderdude]

I'll agree with the others on this. A compression test of the engine should be first, its simple and inexpensive to do this, purchase a harbor freight screw in style gauge or rent/barrow one. Next on my list would be to determine weather the drive ratio (& prop diameter/pitch) is correct for your type/size boat, someone could have put a different drive on for whatever reason. Posting some detailed pics will help

[mister_larry]

In the absence of a slipping prop (unlikely) it almost sounds like the boat is not getting on top of the water. You give it more throttle to get above 3100 RPM, it sounds like it's working harder, but doesn't go any faster? Could you just be plowing water?

Does it have trim tabs? Have you tried a comparison run with them in full up and full down position, at a pre-determined RPM, with a stop watch and an identified distance? If there is no difference you might make sure the trim tabs are working. If they are, you might look into the weight distribution of the boat.

OH, and make sure the outdrive is all the way down !! No obstructions.

If you want some help, and light reading for future projects, pick up THE book: visit fuelishpleasureboats.com

[Lorimer]

Our 84 contessa came with an aq260 and a 1.95-1 ratio duo prop leg.

Unknown to us at the time it also had C4 props which limited us to 3100 rpm, eventually ruining the engine due to predetonation.

With the new aq260 and B2 props we now reach 26 knots at 4300.

Not sure if this relates to your situation but it's one possibility.

Good luck