How fast should my boat go

[studders]

Hello, I have a 1989 Baja islander 190 with a mercruiser 3.0 engine. I was just curious how fast should this engine go. When I have it wot and only about 350 lbs in the boat sometimes less weight I top out about 31mph. That's a pretty good speed for the water and I don't want to drive like 60 but I would think it would go some what faster than 31. I keep it tuned up, oil changed, spark plugs and lower unit oil and all that good stuff. Again I was just curious if that was it or should it go a little faster. Thanks

 

[DaveG55]

Kinda need more information than that.
What prop is on the boat? Diameter, pitch, number of blades, material it's made of?
What is your wide open throttle (wot) rpm?
Where do you boat and what are the water conditions
I don't mean this question to be condescending but we don't know your experience and the question matters. So, here goes, are you trimming the outdrive up properly?

I'm no expert but I would expect you top speed to be in the 40-45 mph range. Depending on prop, trim, load, water conditions, etc.

 

[studders]

Kinda need more information than that.
What prop is on the boat? Diameter, pitch, number of blades, material it's made of?
What is your wide open throttle (wot) rpm?
Where do you boat and what are the water conditions
I don't mean this question to be condescending but we don't know your experience and the question matters. So, here goes, are you trimming the outdrive up properly?

I'm no expert but I would expect you top speed to be in the 40-45 mph range. Depending on prop, trim, load, water conditions, etc.

I honestly could not tell you prop is on the boat, diameter pitch. It does have 3 blades and is a stainless steel blade if that is what you are referring to as the material. My wot rpms is about 4000-4100. I do most of my boating at Brookville lake in Indiana and at times the water can be somewhat choppy, but can still cruise. Last week I went to lake Monroe in Indiana and no one was out there. the lake was as calm as can be and like a sheet of glass and that is where I topped out at 31. I do mess around with the trim a little but don't trim it up too far because of the trim limit switch.

 

[Fastatv]

I honestly could not tell you prop is on the boat, diameter pitch. It does have 3 blades and is a stainless steel blade if that is what you are referring to as the material. My wot rpms is about 4000-4100. I do most of my boating at Brookville lake in Indiana and at times the water can be somewhat choppy, but can still cruise. Last week I went to lake Monroe in Indiana and no one was out there. the lake was as calm as can be and like a sheet of glass and that is where I topped out at 31. I do mess around with the trim a little but don't trim it up too far because of the trim limit switch.

I think the 190 means a 19 foot boat. I wouldn't think you could get 40mph out of her, but it might. Your WOT rpm's should be between 4600 to 4800. So the 4100 is def on the low side. Could be you have the wrong prop installed, however, there are many variables in regards to an engine not achieving the recommended max rpm's. Please see the attached, it will explain some things for you...item # 15 I think. Good luck. http://forums.iboats.com/forum/engi...es-outdrives/295720-adults-only-no-exceptions

 

[studders]

This is probably a rookie question but how do I tell what size prop pitch diameter my propeller is? Will it say it somewhere or do I measure?

 

[thumpar]

There should be a stamping on it. Usually around the hub or on the end. It won't say the exact pitch/size but will give you a number so you can look it up.

 

[Villain lll]

The manual shows 4200-4600 for that 3.0. Also, if your prop is a Mercrusier brand, the pitch is stamped on it. I would expect to see 35-38 mph at best.

 

[stonyloam]

Your trim has a lot to do with it, you should trim for maximum rpm at wot. Trim a bit and watch the RPM take your time the changes occure slowly.

 

[Rick Stephens]

My 17 foot fiberglass 3.0L tops out around 33 MPH with a 17 pitch prop at 4600 RPM. I never thought that was as fat as others have posted, but the 3 liter isn't a lot of HP if the boat is at all heavy or pushing a lot of water resistance.

 

[studders]

I looked at the prop I have on there now and I'm going to have to do some searching on the numbers that it has on there. It is a after market stainless steal though. I do mess with the trim but I don't trim it up a lot. The boat isn't too heavy but it isn't light either. Off the top of my head I cant remember the exact weight on it. I guess what I top out isn't all that bad. It's a nice cruising speed and I'm not out there racing anyone. Just cruising the lake and letting my kids tube and wakeboard. When they tube and wakeboard I only keep the speeds about 20 or so.

 

[HT32BSX115]

Howdy,


You should probably have a look at the following thread (also located at the top of the I/O forums list)
http://forums.iboats.com/forum/engi...-repair-i-o-and-inboards/473314-faq-for-i-o-s

Look particularly at #14


Cheers,


Rick

 

[BruKen]

Top speed and and WOT/prop size isn't always synchronous. I have a 87 19 foot sea ray cuddy which is heavy with a 3.0l Mercruiser on a 2:1 reduction MR leg. A good WOT prop is the Quicksilver 14x19, a good ski prop 14x17 will jump out of the hole but for fast and distance planing I have a over propped 14x21. WOT on this is 3900 rpm but will plane nicely at ~2800 to 3000rpm at ~25mph and the engine runs sweetly. With this prop she will hit 37mph. Fuel economy is improved for distance on cruising speeds but the engine is also loaded more. A 14x19 will only get me to ~30mph and the engine seems to be revving uneccessarily high especially when on a gentle plane. Of course over propping is not recommended for engine longevity, but I have pointed this out so you can see the balance and compromises when it comes to your style of boating and what manu. recommendations etc may be based on.

 

[Walt T]

Verify tach and verify speed first with GPS

 

[jerryjerry05]

The weight and size shouldn't be a concern unless the hull and floatation is saturated.
They wouldn't under power a boat from the manufacturer.
Some seem that way, but it should go about 35+
Under the nut and washers there should be a # with the pitch engraved in it.
Set up right with the correct prop and trimmed correct.
Your motor should get about 44-4500 up to 4800rpms.Depending on the specs for that motor. Get a factory manual.
Aftermarket Clymer or Seloc are ok but the factory is better.
.Hit both buttons at once and see if that helps???
If you have a SS the equivalent alum. prop is 2 pitches higher.(a 19ss is the same as a 21 alum. or close)

 

[HT32BSX115]

Top speed and and WOT/prop size isn't always synchronous. I have a 87 19 foot sea ray cuddy which is heavy with a 3.0l Mercruiser on a 2:1 reduction MR leg. A good WOT prop is the Quicksilver 14x19, a good ski prop 14x17 will jump out of the hole but for fast and distance planing I have a over propped 14x21.

Props (pitch) will (of course) vary from one boat to another. But what the engine manufacturers recommend doesn't (vary, that is).

They recommend selecting a prop that will allow the engine to achieve (but not exceed) maximum rated RPM (or in the recommended range) at WOT.

They further recommend doing the "test" with the boat typically loaded with "normal" amounts of gear, people and fuel........AND doing this at the pressure altitude where you'll normally want to operate. (I.E. don't prop it for the Sacramento River [SL] when you're planning to go to use the boat at Lake Tahoe [6000' MSL alt)

If you're doing this with an older unknown boat, you need to ensure that the engine is running correctly, the hull is not waterlogged etc etc etc....

Verify tach and verify speed first with GPS

YES.................. and if you don't, you're wasting your time fooling with props.......


//