270 Sundancer Performance

N

No Name Sea Ray

New Member
Jul 13, 2009
73
Annapolis, MD
Boat Info
1997 Sea Ray 270 Sundancer, 8.1L Repower
Engines
8.1L Repower w/Bravo III
First post here. Thanks for having me.

I have a 1997 270 Sundancer and with 5 adults or more on the boat I cannot get up on a plane. (Average weight people)

Is this normal? What kind of planning do you get? Top speed?

I know it is a heavy boat and that all the people are in the cockpit seating which keeps the weight way back and the worst place, but I hate to ask guest to move forward.

I just want to see the performance others are getting before I go making changes.

The original 7.3L/330hp engine was replaced last year with a new 8.1L/375hp so I should have plenty of power.

The Bravo III outdrive lower was replaced several years ago with a remanufactured unit. 2.0 Ratio I believe.

I do not know the size of the props.

Once I know what performance I should expect I’ll start looking into the drive ratio and prop size or rebuilding the props.

Thanks,

Matt
 
Please explain what you are doing (throttle, trim, tabs, etc) when trying to get on plane.

Did you search other threads on this forum that had the same problem?
 
not normal. what is wot?
 
I did a search and did not come with anything that applied.

I am just trying to bring it up on an easy plane, slowly rolling on to full throttle, drive all the way down, and trim tabs tried in all positions.

The hull is clean with a smooth coat of bottom paint and the motor runs strong.

My WOT is 4800-5200 and the specs for the motor are 4400-4800. So I am running a little high here.

The props are supposedly original.
 
Sounds like you're doing everything correct. Where do you have the drive and the tabs when trying to keep it on plane? General rule is drive at about 1/4 (assuming your gauge reads correctly), tabs as needed. Don't be afraid to use the tabs to help keep it on plane.
 
We have similar boats and power packages. My boat needs lots of tabs to stay on plane and likes the drive trimmed pretty much all the way down. I can not stay on plane below 3400 rpm at about 22mph by my GPS.
 
No Name Sea Ray said:
I have a 1997 270 Sundancer and with 5 adults or more on the boat I cannot get up on a plane. (Average weight people)
Click to expand...

I get on plane at 3400 cruise at 3800 rpm 26-28mph. No trim tab. I got an increase of 200 rpm when I switched to a 4 blade prop but much better acceleration. My boat is always heavily loaded. WOT 4600 @ 34-36, With old three blade 4400rpm and 37-38
 
I have a generator and A/C which adds a lot of weight. I could probably retract the tabs at 3600-3800rpm but I never run that hard.....burns to much gas and doesn't feel much different than 3400 rpm.
 
Ditto on the genny and a/c plus 4 batteries. I can plane @ 3100 w/tabs full down. Usually cruise @ 3400-3600 at 26-28 mph, trim and tabs to match conditions. This is with 2 adults and 2 children.
 
It is good to see some of your rpm ranges for plane and cruise. I'll need to note mine next time I am out.

I have no problems with 2 adults and 2 under 100 lbs children, my normal family. Above that I start to have problems getting on a plane. Once on a plane I have no problems either. The one thing the new motor added was the ability to keep it on a strong plane in rough seas and all the time without messing with the trim tabs all the time. Therefore I can use the tabs to really fine tune the ride.

My feeling is my rpms are too high and that the replaced lower unit is the wrong ratio and or the props are wrong or out of tune. Visually the props look good.

Where can I find out the original props size and drive ratio?

I have the gen, AC and 3 batteries.
 
Last edited:
Since you have a Bravo III, you can try moving the "celery stick" (spacer that goes in the oval hole where the trim rams connect to the back of the drive) to the rear position. This spacer is normally positioned towards the front of the boat. By moving it to the rear position, it will allow you to pull the drive a little farther down, which in theory would help you push the bow down to get up onto plane.

The down side to this is that you might get "undesirable" results when the boat is NOT fully loaded down. To compensate, you could always raise the drive up a little before accelerating onto plane when you have a "normal" load on the boat.

Its worth a try as a test, and it is free!

Michael
 
Skibum- this is good info, thanks. I seem to remember that the mechanic had to adjust this up because of the newer revised exhaust boot/cup instead of the original boot/hose. Mercruiser revised the part at some point. Could be an issue. I'll have to play with this. Do you know if it can be adjusted in the water?

Otherwise, I found the original props size and drive ratio so I can verify with whats on the boat now. Did some searching on this site and SeaRay.com to find it here- http://www.searay.com/Page.aspx/pageId/10552/Manuals.aspx
You just have to enter in your info then they let you right in for the info. Good support.

Thanks for all the replies, I am getting somewhere now.

Matt
 
Update- I bought new 28P props on ebay for $520 including shipping, unopened box. These are the brand new Bravo III props that the front prop is 4 blades and the rear prop is 3.

They fit right on no problems. Original props were 26P

With 2 onboard and 1/2 tank of gas it did a nice steady climb up to plane, without the normal hump to climb feeling. Lowered the rpms 200.

Not exactly sure of the true rpms because I think I am getting a bad reading. Need to verify this.

On the outdrive pin setup- we thought it was in the right place but I think it is not. To get the drive to be in lowest position the bolt that holds the hydraulic cylinders needs to be in the aft position. (SkiBum- I had forgotten what you wrote above.) So I still want to change that.

Still need to test with 5+ people on. I'll follow up after that.

Great deals on ebay if you are looking for spares. Dealers are hurting and/or closing and selling cheap.
 
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