1990 Sea Ray 160, Mercruiser 3.0 with Alpha one gen 1

[LEONS]

Hi All, I am new to this forum. I have recently bought a 1990 Sea Ray 160 with a 3.0 mercruiser inboard engine. I live in Uganda so parts are not available and I typically order from the US. this in itself is not a problem however mistakes by ordering the wrong parts could be very costly.

I do not think that the boat is propped correctly as it lacks power on the low end (get up and go). when just two people in the boat my current WOT is 3900 RPM which I believe is also too low (recommended 4400 to 4800 rpm) the current prop is an aluminum 3 blade with 21 Pitch.

Would anyone be able to recommend the correct prop diameter and pitch? we would like to use the boat for skiing so top end is not crucial.

I thank you for your advice in advance.

Kind Regards
Leon

 

[Scott Danforth]

Welcome aboard

For cruising, a 19p

For watersports, a 15p or 17p

With the 3.0, you run out of engine quickly, so you usually need a prop for every occasion

 

[LEONS]

Welcome aboard

For cruising, a 19p

For watersports, a 15p or 17p

With the 3.0, you run out of engine quickly, so you usually need a prop for every occasion

hi Scott, thank you very much for your reply. Know that it is difficult to say but if you were to use the boat for majority water sports and occasional cruising would you go for a 17p or would you go all the way down to 15 pitch prop?

 

[Bondo]

hi Scott, thank you very much for your reply. Know that it is difficult to say but if you were to use the boat for majority water sports and occasional cruising would you go for a 17p or would you go all the way down to 15 pitch prop?

Ayuh,..... Welcome Aboard,...... I'd go to the 15" in that case,.....

 

[Scott Danforth]

hi Scott, thank you very much for your reply. Know that it is difficult to say but if you were to use the boat for majority water sports and occasional cruising would you go for a 17p or would you go all the way down to 15 pitch prop?

I carried 3 props with me in my boat that was powered by the 3.0. a 15p, 17p and 19p, all stainless the 3.0 doesnt have enough torque to swing a bigger prop and pull skiers. so I used the 15p for skiing, and water sports as well as when I was trolling for salmon. the 17p for general use, and if I needed to go on long trips, the 19p.

 

[Texasmark]

I would also recommend the 15P having had a 3.0 and easily running out of engine when pulling water toys and having several people on board. Since you didn't mention top speed as a requirement it made it easy to choose between the 15 and 17. The 17 would do a half assed job on both counts whereas the 15 would do the water sports well and you'd have to watch your throttle to keep your RPMs in range when running light.

 

[JimS123]

I can't compute the data here. Somting fishy.

We had a 19' Stingray that was originally propped with a 21 pitch Michigan SS prop. It was extremely good, but not perfect. I had then prop re pitched to 20 and it ran close to 4800 rpm, literally jumped out of the water and ran in the high 40's gps. Pulling 2 tubes was a breeze.

I realize that Stingrays are light, but we're comparing a 19 to a 16 here.

My suggestion is to verify that the engine is running up to snuff.

 

[Scott Danforth]

the OP's boat weight and size is comparable to the Avanti I owned with a 3.0 OMG. 19P prop was 4600 RPM and just a tick over 40mph. a 21p brought the engine to its knees with a maximum RPM of 3800 and it rattled like crazy due to detonation from lugging

@JimS123 your bigger/flatter/lighter stingray is a different hull all together with a much flatter dead-rise that would probably spin the prop like you mentioned. however in anything over a 6" chop, the ride in the larger deadrise searay would be a lot better.

 

[LEONS]

Hi All, thank you very much for all the replies, the advice is dearly appreciated. one more question before placing the order on the 15P prop. Would a 17P - 4 Blade Prop make any difference to the boats versatility? maybe still good low end for watersports but also a bit more in the top end for cruising?

 

[JimS123]

the OP's boat weight and size is comparable to the Avanti I owned with a 3.0 OMG. 19P prop was 4600 RPM and just a tick over 40mph. a 21p brought the engine to its knees with a maximum RPM of 3800 and it rattled like crazy due to detonation from lugging

@JimS123 your bigger/flatter/lighter stingray is a different hull all together with a much flatter dead-rise that would probably spin the prop like you mentioned. however in anything over a 6" chop, the ride in the larger deadrise searay would be a lot better.

My Stingray was a 1984 and it had a 17 deg. deadrise. I looked in my collection of catalogs and I couldn't find a SeaRay 160, but there were several years back then that they made a 175. That hull also had a 17 deg. deadrise and it was several hundred pounds lighter than my 19 footer.

 

[Texasmark]

Hi All, thank you very much for all the replies, the advice is dearly appreciated. one more question before placing the order on the 15P prop. Would a 17P - 4 Blade Prop make any difference to the boats versatility? maybe still good low end for watersports but also a bit more in the top end for cruising?

2 things working against you here. 4 blades have more bite and need more to drive them. 17P vs 15P the same...more to drive it. 2X wrong direction.

 

[LEONS]

clear thank you. I will order a 15p 3 blade prop as per the recommendations above.

 

[Scott06]

Hi All, I am new to this forum. I have recently bought a 1990 Sea Ray 160 with a 3.0 mercruiser inboard engine. I live in Uganda so parts are not available and I typically order from the US. this in itself is not a problem however mistakes by ordering the wrong parts could be very costly.

I do not think that the boat is propped correctly as it lacks power on the low end (get up and go). when just two people in the boat my current WOT is 3900 RPM which I believe is also too low (recommended 4400 to 4800 rpm) the current prop is an aluminum 3 blade with 21 Pitch.

Would anyone be able to recommend the correct prop diameter and pitch? we would like to use the boat for skiing so top end is not crucial.

I thank you for your advice in advance.

Kind Regards
Leon

I had the exact same boat for 20 years. Year 21" is too much pitch for your engine

I used a 18" 4 blade michigan wheel votex for tubing/cruising

I used a 16" 4 blade michigan wheel vortex for skiing

Both worked very well and were relatively inexpensive being aluminum

Also make sure you engine is in good working order

 

[JimS123]

clear thank you. I will order a 15p 3 blade prop as per the recommendations above.

First of all, check your tach to be sure you are getting the correct numbers. I agree that 21p is too tall, but I think that a 15 will over-rev the engine.

It might be OK for skiing, but don't go WOT until you verify that your rpms are correct.

My current SeaRay gave data that made no sense. I found out that the tach setting was wrong. A simple change in the switch position corrected it.

 

[QBhoy]

My Stingray was a 1984 and it had a 17 deg. deadrise. I looked in my collection of catalogs and I couldn't find a SeaRay 160, but there were several years back then that they made a 175. That hull also had a 17 deg. deadrise and it was several hundred pounds lighter than my 19 footer.

Stingrays always punch way above their weight. Such fast things for their power, I’ve always thought. But also agree that there is no way he should be going to a 15”.

 

[Scott06]

Stingrays always punch way above their weight. Such fast things for their power, I’ve always thought. But also agree that there is no way he should be going to a 15”.

Agreed my sea ray was a 170 i think (1991) i ran both a 3 blade 17” black max and the 4 blade 16” voretx, cannot imagine going lower in pitch as either of those loaded would hit 4800 easily .

there were a couple different 3.0 s offered i think one at 115 hp and the lx at 135 Hp…

 

[JimS123]

Agreed my sea ray was a 170 i think (1991) i ran both a 3 blade 17” black max and the 4 blade 16” voretx, cannot imagine going lower in pitch as either of those loaded would hit 4800 easily .

there were a couple different 3.0 s offered i think one at 115 hp and the lx at 135 Hp…

The original 3.0 was 140 HP. About the time they added electronic ignition and maybe other changes (I dunno) it was downgraded to 135. The lower HP models at the time were 2.5 liter engines.

If that little Searay with 2 people aboard can't run a 19p there is another issue. Its an oldie boat, maybe the hull is full of water.

Regardless, more investigation is in order before lots of money is spent.

 

[Scott06]

The original 3.0 was 140 HP. About the time they added electronic ignition and maybe other changes (I dunno) it was downgraded to 135. The lower HP models at the time were 2.5 liter engines.

If that little Searay with 2 people aboard can't run a 19p there is another issue. Its an oldie boat, maybe the hull is full of water.

Regardless, more investigation is in order before lots of money is spent.

Yes early 70 s was 140 hp Rating .
My 1991 boat(1990 engine build date)lx was 135 hp not sure if the diff was prop vs flywheel that the 140 was. There was no 2.5 in 1990 ( per Don S last year was 89) the 115 or 120 hp 3.0 ( non lx ) i belive had the 3.0 block with the smaller port older design 2.5 head on it.

you are correct it could swing a 19” very well, 4600-4700 or so, never would have swung a 21 ” well at all. This was a boat my folks bought 4 years old and by the time it was passed on to me we had it 21 years.

 

[LEONS]

thank you for all the replies above, I am now even more confused... ; - )
it would seem that the consensus would be that 17p would be ok for water sports and better for cruising? a 15p would be ok for skiing but not good for cruising at all. would everyone agree that a 17p 3 blade alu prop will work well enough for skiing and cruising - not ideal I get that but more versatile compared to 15p?

 

[Scott Danforth]

Prop vs flywheel hp

Only you can tell us the performance you get with your boat and the prop. Each of us have different boats, different hull shapes, etc. Out experiences all differ slightly

With one exception, most of us ran multiple props on a 3.0 to get the performance needed for the task at hand