SeaRay 21'

[Greendiver]

New to me this year is a '96 SeaRay 210 Bowrider with a 5.7L MerCruiser. Not sure but I think is rated at 220hp.

I'm pretty sure I'm losing some of the top speed and fuel efficiency as I have no problem spinning it up past recomended WOT numbers as printed on the engine decal. Looking to see what I can gain by looking at a different prop selection.

Realizing that I don't have all the numbers I need, I'll put what is fresh in my head and add more later..

Running WOT the boat will hit 49mph at approx 5400rpm, spec is 4200-4800rpm I think. I only stayed at WOT for a short bit so I'm not sure how far she'd still pull. At 4500rpm and trimmed up we are at 43mph. The tach numbers are confirmed and the water speed is GPS.

The prop is a stainless quicksilver 48-16316A4 19p.

I'll get the production weight numbers (they are all I'll have) and post those later when I can.

Thanks!

 

[Greendiver]

Re: SeaRay 21'

Hhmmm...

Reading the installation manual for the engine it shows the engine having the rev limiter come in at 4900 rpm regardless of hp rating. How the heck did I get over 5K? Perhaps a backup tach for my backup?!

 

[backyard mechanic]

Re: SeaRay 21'

I'm curious... what is your question? Sounds like you need to re-prop to get the RPM down. You need to loose about 600 RPM so 2 pitches up will be a bit too much (considering 400 decrease with each inch of pitch). IMO, 1 size up in diameter might be just what the doc ordered. I would really hesitate to go away from a cupped prop.

Depends a lot on what you are doing with the boat. Skiing or trolling; it does make a lot of difference.

 

[Greendiver]

Re: SeaRay 21'

Well my question is really two fold in I'm pretty sure I could put a bit more aggressive prop on but was looking for confirmation. And second, how much of a jump in prop I should consider.
I would imagine I should be targeting the low end of the rpm range when loaded heavy. Am I wrong on that?
Thanks for your input!

 

[hwsiii]

Re: SeaRay 21'

Diver, borrow a mechanic's tach and make sure your present tach is reading the right RPM, because in my opinion your tach is WAYYYYY off. One you get that resolved come back and we will help you.



H

 

[Greendiver]

Re: SeaRay 21'

I'll recheck the numbers when I get out again. The time I got 49mph at 5400rpm I was only using the boats tach. But the second set (43/4500) was with a DVOM and inductive pickup, it matched the dash tach. I will be more than happy to get her out on the water AGAIN. The chores never stop!

 

[Greendiver]

Re: SeaRay 21'

Well it was a chore but I got out on Lake Michigan tonight and the water was awesome! Almost glass flat, with a great sunset to boot.
Here are what I have running, again with an inductive tach and Lowrance automobile GPS.
4 people, almost full on fuel, and a dog.
44mph @ 4500rpm
47mph @ 5000rpm - WOT
Now I've discarded the previous 5400rpm as I ran WOT tonight and could not hit it with the inductive tach, dash tach error as you suggested I believe. The literature indicates the rev limiter at 4900 and I didn't hear or feel anything, is it a pretty subtle timing / fueling reduction like max speed on an auto or is it a pretty noticable event when the limiter is reached that I couldn't miss?

Some of the other numbers are:
5.7L EFI 220HP
Suggested RPM range 4200-4600 (the 4800 above is for the 250hp version)
Dry weight 3300lbs
Max fuel 35gallons
The gear ratio I cannot find in any of my literature but suspect it is 1.47:1 or 1.50:1.

Looking at this I don't believe it is as far off as I initially thought, although I do have a feeling that I am against the limiter and don't know it.

 

[Greendiver]

Re: SeaRay 21'

Bringing this back up for some of the Sunday cruisers!

 

[Bondo]

Re: SeaRay 21'

The prop is a stainless quicksilver 48-16316A4 19p.

Ayuh,... Step up to a 21" prop...

 

[Greendiver]

Re: SeaRay 21'

Are there any special considerations if I would switch from SS to AL? Should I consider one of the 4 blade props available?

 

[Bondo]

Re: SeaRay 21'

Are there any special considerations if I would switch from SS to AL? Should I consider one of the 4 blade props available?

Ayuh,... 4 bladed props are good for watersports, or stern lift, but you make no mention of handling issues or concerns...
If you stick with round eared props, I don't think there'd be an issue going to aluminum...
I'd still go 21"...

 

[dlayman]

Re: SeaRay 21'

(bump ttt) for Any updates?

 

[Greendiver]

Re: SeaRay 21'

No updates to speak of yet. The boat is so grossly mis-propped that I can't stand to use it. LOL, just kidding... I'm getting ready to head to the launch and wait out some weather hoping to go out and maybe get a dive in this morning!
We've been using the boat for cruising, a bit of tubing/skiing, and some diving so the prop being off a bit hasn't hampered the fun. I'm thinking for now I will get the most bang for my buck on a new _________. (bimini, humminbird si, etc).
I have to admit I have thought that when I do match a prop to my boat, a four blade may be in the running. She's not as good as I think the she could be on turns and rougher water.

PS We have seen more awesome sunsets lately, you should try and catch one. I think there's one scheduled for your area tonight!

Gotta run!