2000 Johnson 150 Oceanpro on a Glastron Sea Fury v216

[reiddo1]

Largely because of what I have read on this site, l am led to believe that I have excessive prop slip. My WOT engine speed is 5200 RPM and my GPS boat speed is 36 miles per hour. The engine is in excellent mechanical condition and according to Solas the 14.5 by 19 pitch prop is theirs from the number on the prop hub. Since I can stand on the prop blades and turn over the engine with all the plugs installed leads me to believe that I do not have a spun hub and indeed the prop is like new. I have raised the engine to the top hole and do not have much trim range at WOT before it starts to ventilate. The anti ventilation plate is about 1 inch above the bottom of the keel. This last position has been arrived at one hole at a time and I will probably keep it there for some time.

I have read where in cases like this, a prop with cupping can get around this slip issue. Is there a prop which will reduce my slip and improve on my top end. Hole shot is absolutely superb with up to four onboard with full tank and fishing gear. The number on the current prop is 390821 and my lower unit ratio is 1.86 to 1. Any comments are appreciated.

 

[jakedaawg]

36 mph in a 21'6" boat with only 150hp sounds about right to me. Glastron is not a light boat

 

[reiddo1]

The boat dry weight is 2200 lbs plus 390 lb for the engine. Not really that heavy. The weight is not an impediment but maybe the hull design being a 1997 vintage.

 

[reiddo1]

Correction the boat was made in 1979 not 1997

 

[bob johnson]

your boat could very well be laidened with 3-400lbs of water that has been absorbed into the flotation under the floor.... this happens a lot on older boats!!!

have you weighed you hull, or is that figure from literature???

PS many people think those motors will run 5800 rpm a lot better..

is your motor a FICHT engine????

bob

 

[reiddo1]

Not a FICHT but carbureted; the boat has no flotation; I removed it. The weight is from literature. OMC suggests 4500 to 5500 rpm operating range. I would be concerned running it at 5800. What do you think?

 

[bob johnson]

I had heard that the people in the know pushed those style outboards regularly to 6000 rpms.... I run my v4 115 to 5600-5900 at WOT..... now I don't often take her up that far....but that's what she is set up for...I have temp gauges....I just pay attention if I am screaming along on flat water...the word was those motors liked that higher rpm...I bet a lot of people coke up their motors running WOT at 4500 rpms!!!!!!!!!!!!

bob

 

[reiddo1]

That is interesting; I was going to try another prop (aluminum) 15x17 pitch but concerned that 2 inch less pitch would push my engine into an overspeed situation.

 

[sutor623]

That is interesting; I was going to try another prop (aluminum) 15x17 pitch but concerned that 2 inch less pitch would push my engine into an overspeed situation.

Nah, going two sizes down will raise your rpms about 400rpms (theoretically) and I think that would be perfect for that motor.

 

[steelespike]

390821 is an OMC number left hand rotation stainless prop.
Not Solas.
Your slip calculates at 28% normal would be about 12%.
Seems odd for a ss prop to have high slip.If we assume
speed is accurate slip is either inaccurate tach or real slip.
From your description" Not much trim range" and the high slip number
I would suggest you lower the motor one hole.
Does the boat get up on the water as it should?
About 1/3 to 1/2 in the water?
Does it respond to up trim?
Is the bottom clean and smooth no bulges or hollows?
Is there a foil on the motor?

 

[Chris1956]

I have a similar boat/motor package. I get about 39MPH with RPMs at 4600 or so. Dropping the motor to allow more trim, w/o blowout could raise your speed, but you will need to take measurements or RPM and speed at various throttle settings and compare them.

 

[reiddo1]

390821 is an OMC number left hand rotation stainless prop.
Not Solas.
Your slip calculates at 28% normal would be about 12%.
Seems odd for a ss prop to have high slip.If we assume
speed is accurate slip is either inaccurate tach or real slip.
From your description" Not much trim range" and the high slip number
I would suggest you lower the motor one hole.
Does the boat get up on the water as it should?
About 1/3 to 1/2 in the water?
Does it respond to up trim?
Is the bottom clean and smooth no bulges or hollows?
Is there a foil on the motor?

I called Solas and gave them the number on the prop hub; the tech I spoke with said it was their prop. Tach is brand new and set on 6 poles for that engine. On the top hole for mounting I only get blow out if I turn the helm hard at greater than cruise speed. Incidentally I saw no changes in speed at WOT going from the bottom hole to the top in 1 hole increments. Hole shot performance is superb as it has been for all engine mount positions. The hull is clean with no paint and my speed is as accurate as a Garmin GPS gives. There was a foil on the motor when I bought it used 3 years ago but I took it off on my second trial because my hole shot is excellent. If indeed my slip numbers are at 28% and I have no reason to dispute that, I suspect the slip is inherent in that prop design. I am hoping I can find a prop to reduce my slip and hopefully get greater range and economy from a tank of fuel.

 

[reiddo1]

I have a similar boat/motor package. I get about 39MPH with RPMs at 4600 or so. Dropping the motor to allow more trim, w/o blowout could raise your speed, but you will need to take measurements or RPM and speed at various throttle settings and compare them.

I have seen no change in speed at WOT on any of the mounting positions I have used. My only observation is that my trim range for blowout decreases the higher the engine is mounted, which is expected. The blowout I allude to comes only when I give it hard helm or continue trimming up. Once blowout starts I merely trim down until it disappears. Hard turns to port or starboard at WOT will cause some ventilating but under normal use I do not experience it. I only raised the engine to the uppermost hole a month ago and did so because I wanted to satisfy all those who maintain that engine height should be 3/4 to 1 inch above the keel. I may go back to the next lower position but as the snow is now falling my boat is secured with a tarp for the winter.

 

[Chris1956]

Does your boat have the same Vee shape from bow to stern or does it have less Vee at the stern?

 

[reiddo1]

Less v at the stern

 

[Chris1956]

OK, Less Vee at the stern means that you can usually get the bow to lift raising speed. Dropping the motor down on the transom to allow more trim can lift the bow. A prop with more rake can also lift the bow. Does the Solas props have good rake?

 

[reiddo1]

I do not have any experience in what is required in my prop for best results. I do not know whether my prop has the required rake you refer to. All I can tell you is:

1. There is no noticeable difference in speed, hole shot performance, WOT RPM, OR handling for any of the heights which I have mounted the motor, except that as the engine is raised my trim out range before blow out becomes less. With that said I would suggest my slip changes are insignificant also over these heights.

2. My objective is to get the very best engine set up for my boat and if indeed my 28% slip is not desirable, I need to know what prop would give me an acceptable slip. Hand in hand with that objective is greater range on a full tank of fuel and increased speed at WOT if required.