'87 Sundancer 250 prop recommendations?

ferguda

ferguda

New Member
Aug 19, 2009
20
Winnipeg, MB Canada
Boat Info
1987 Sundancer 250
Engines
Mercruiser 230 w/Alpha I
I believe I have a 16 pitch 3 blade aluminum (original?) on our 1987 Sundancer 250 with 230 Mercruiser Alpha 1. Any suggestions for a replacement prop for general useage?
 
What is your WOT with that prop? Are you looking for a prop to pull skiers or just general cruising?
 
Are you unhappy with what you have now?

What would you be looking to accomplish with a new one?

If you just want to read up on more general information, try doing a search - there are a TON of threads about props.
 
I'm mainly looking for a replacement as this one is a little beat up. I'm not sure if it's the original and think the RPMs are a bit low. That being said I'm relatively satisfied with performance. A little more speed would be nice but I don't know if possible with this engine or dropping RPMs more. Top speed is around 30 MPH.
 
well your RPM's are a little low, they should be 4200-4600. If your prop is beat up a bit then that will affect performance but you should be shooting for around 4400. I have a Merc 260 and it runs best with a 16x16.
 
OK, then in that case let's start with your WOT RPM, as Sundancer said.

Props can be repaired, as well.
 
I'd say the rpm's are too low as well. If you have had a tune up recently, have no bottom growth and the boat is loaded with it's "usual" load then I think a lower pitch is in order. Yes, a beat up prop will impact performance, but we're trying to gain 400 rpm. A 16 pitch is part of the equation, we also need the diameter and whether the blades are cupped. Sea Ray and Michigan wheel have prop charts that will help you identify a prop to start with. Then you can massage it from there based on performance. Some prop shops will allow you to "test" a prop to see how it works. Of course, if you break it you buy it!
 
Lazy Daze said:
OK, then in that case let's start with your WOT RPM, as Sundancer said.
Click to expand...

Oops. Skipped over the part where you already mentioned that.

Just for clarification - how long have you had the boat? Has the WOT always been 4,000? And, are you trimming up?
 
I just got the boat a month ago, it had been in storage for about 1.5 to 2 years. The RPMs were lower until I discovered the trim wasn't adjusted (the person who put the boat in the water for me didn't get the drive all the way down). Adjusting the trim brings RPMs to a max of 4000. The only marking I could find on the prop says "16P". I haven't done a full tune-up yet...just the basics to get it in the water. Once I get it out of the water for the winter, I'll be able to get all the prop specs such as diameter as I haven't been able to determine if it's the original prop or not (don't know what the factory put on).
 
I just looked up the Sea Ray prop chart and it lists a 16x13 prop. I presume this would be 16" 13pitch?
 
ferguda said:
I just looked up the Sea Ray prop chart and it lists a 16x13 prop. I presume this would be 16" 13pitch?
Click to expand...

Yes. But, never trust those charts as gospel. Too many changes made during the model year.

However, in this case it seems to be just about right. Dropping to a 13" should bring your RPM's up where they need to be. Again, this is assuming you are trimming up. I'm not clear as to whether or not that's what you meant in your above post.
 
Yes, I've trimmed up/down and that's the best I got. This weekend I'll see what max RPMs I get in neutral to see if there's any difference while not under load.
 
ferguda said:
Yes, I've trimmed up/down and that's the best I got. This weekend I'll see what max RPMs I get in neutral to see if there's any difference while not under load.
Click to expand...

Ummm...dont do that. It wont really tell you much anyway cuz theres a huge difference between engine under load and not under load. Is it running smoothly at 4000 or WOT or sputtering and struggling? What about trim tabs? Are they all the way up? Start with your drive all the way in and your tabs all the way up. Bump the drive out just a little and watch your Rpms rise a bit...but too much and the prop will break loose so just use a little drive trim at a time. You shouldnt need tabs at all to plane out. If your prop is damaged and youre running smoothly at WOT then I would look there if its the CORRECT prop.

Now...based on the prop chart and the info you told us....you are overpropped. If your prop is a 16p like you said, then youre 3" too high on pitch and every inch of pitch equals roughly 200 rpm. Soooooooo if you currently have a 16" diameter x 16 pitch prop..you would be technically restricting your engine from hitting its prescribed 4600 WOT rpms by.....DING DING DING...600 rpm! LOL. I think you'll see that if you pull the prop (which can be done in the water sitting on the swim platform) and swap in a 16x13p you'll find your missing rpms. Please let us know what you find.
 
ferguda said:
I just looked up the Sea Ray prop chart and it lists a 16x13 prop. I presume this would be 16" 13pitch?
Click to expand...
Yep! That's what Sea Ray specs for big heavy boats.
Quicksilver Alum 3 Blade come in 16x13, 16x14, 16x16.
Good news is there about the cheapest good quality alum props on the market
 
If your current prop needs to be fixed by a prop shop, they may be able to "adjust" it somewhat. Sometimes they can rearrange the blades to a different configuration assuming it's relatively close to begin with. Check with them and see what they can do! Maybe it can be switched to a 16 x 13?
 
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