wot

the increased deadrise on the newer model woudl make it even harder to get on plane...

assuming the speeds you quoted are GPS which you ahvent' confirmed, your dealer is full of it. there is no way a 26 footer would top under 30kts... Call sea Ray directly to get performance data for this boat and have the dealer do something about it.
 
tanq. my last boat, a heavy 37 footer with twin vee drive, coudl stay on plane at 16 kts with full tabs and a light load.

Geez...Maybe I've got some issues with mine that I'm not aware of.
Even with a light load and tabs down I can't stay on plane at that speed.
I wish I could remember what my RPM's were at that speed but it's been a sbnowy winter here and I fear the snow has taken its toll on my memory lol I'll have to pay attention to that when I get it back in the water this spring. I do remember however that with both engines at 3200 RPM's I'm going 28 mph by GPS.
It seems to me that if I remember right that at about 2700-2800 that I'm going somewhere in that 22-23 mph range .... Does any of that sound right to you?
This is a 2850 Cruisers Inc Rogue with twin 350's 260hp. and alpha 1 drives and stainless props although I couldn't tell you right now what the diameter and pitch are. Also it weighs in at 11700 with very little fuel and water onboard. Also....WOT on both engines is 4900-5000 rpm's
 
Do you have a friend with lots of experience with a similar style boat? Perhaps take him for a ride and let him try to set it up on plane.

Without trying to cause offence, I suspect weight and balance and/or technique issue as a strong possibility here. A fresh perspective might help before digging into the possible mechanical issues.

Kev
 
what is wot and how do I determine what a boat's wot should be ?
 
WOT = Wide Open Throttle. You manufacturer recommends a WOT rpm range. For most Mercruisers, it's 4400-4800, some are a little higher. Outboards tend to be 5000 and up.
 
tanq. depends on the boat and power train. Inboards / vee drives have lower WOT rpm, at least the 7.4s did (1998). WOT was 4400 from what i recall... i'd cruise 3600rpm which gave me 20 to 21kts depending on load. at 32 to 33 hundred, i'd get about 17kts. 3600 was the best speed for THAT boat.

Bert, making sure your boat can reach its rated WOT RPM is importnat to make sure it's prop'd right. it's crucial on a diesel boat since overloading can drastically shorten engine life.
 
I have a 2006 270 Amberjack, which has a hull very similar to the 260 Sundancer in question, and the same 350 MAG engine/BIII combination. My weight is a few hundred pounds less, but I carry more fuel so it's about the same.

My performance is much better than what's being discussed with this 260DA. I plane at about 15-16; cruise is 28 mph ** 3900; top end is 35 mph ** 4850 (approx.) My trim tabs are only used to balance to boat side to side and a little to adust the pitch for sea conditions - not to help with planing speed. My deadrise is 21 degres and cruising fuel burn is about 11.5-12 GPH.

I agree with others that those performance numbers are not what they should be and ther something is definately not right.
Your planing speed should be lower than 22 mph, top end should be greater than 28, and the WOT RPM should be more than 4600. That's assuming a reasonable load, but the WOT should still be in the 4800-5000 range.

Also just consider the speed range between planing and top end. Its only a 6-7 MPH range between planing and top-end, and WOT is not a practical every day operating condition. My plane to top-end range is 19-20 MPH. That lower range is just not as it should be. Either there is something wrong with the engine or you have some serious drag issues, like a drogue hanging off the hull.
 
quote:
Originally posted by WastinAweigh

krb,

I have the same boat and engine, with the generator. WOT for me is about 4800 rpms and 38-39 mph. I cruise at 25 mph (GPS) turning 3650 rpms - no tabs but with the drive trimmed. Fuel burn (smartcraft) is 12.5 GPH average - a little higher with full tanks.

Once on plane, I can keep her on plane down to about 16-17 mph and about 3200-3300 rpm's with tabs down and the outdrive trimmed all the way down, assuming that conditions are calm or that I am heading into the seas.

One problem that I had at about 140 hours was a leak in one of the exhaust manifold gaskets. That caused a loss of power although not as severe as what you describe. Do you have an exhaust smell in the bilge when the engine has been running? A leaking gasket can also sometimes make a distinctive "ticking" sound.

Has this always been a problem or is it recent? Do you have benchmark numbers to compare to, by any chance? A lot of problems will cause an increase in fuel burn as one of your first clues.

The 350 is an EFI engine. Is the computer losing power causing it to unlearn your engines settings and run at a default setting? If I remember correctly, the default settings on the module would cause it to run rich. Not sure if that would cause your problem, though, and I am not a mechanic, and did not sleep in a Holiday Inn Express last night.

What is your engine temperature after it is warmed up?

Does it idle smoothly, or does it want to stall? Both warm and cold.

Click to expand...
 
quote:
Originally posted by WastinAweigh

krb,

I have the same boat and engine, with the generator. WOT for me is about 4800 rpms and 38-39 mph. I cruise at 25 mph (GPS) turning 3650 rpms - no tabs but with the drive trimmed. Fuel burn (smartcraft) is 12.5 GPH average - a little higher with full tanks.

Once on plane, I can keep her on plane down to about 16-17 mph and about 3200-3300 rpm's with tabs down and the outdrive trimmed all the way down, assuming that conditions are calm or that I am heading into the seas.

One problem that I had at about 140 hours was a leak in one of the exhaust manifold gaskets. That caused a loss of power although not as severe as what you describe. Do you have an exhaust smell in the bilge when the engine has been running? A leaking gasket can also sometimes make a distinctive "ticking" sound.

Has this always been a problem or is it recent? Do you have benchmark numbers to compare to, by any chance? A lot of problems will cause an increase in fuel burn as one of your first clues.

The 350 is an EFI engine. Is the computer losing power causing it to unlearn your engines settings and run at a default setting? If I remember correctly, the default settings on the module would cause it to run rich. Not sure if that would cause your problem, though, and I am not a mechanic, and did not sleep in a Holiday Inn Express last night.

What is your engine temperature after it is warmed up?

Does it idle smoothly, or does it want to stall? Both warm and cold.

Click to expand...
what pitch props do you have mine are 20pitch cupped
 
The boat is 6200lbs and 19 degrees of deadrise. Sounds like you just need to take the service manager for a cruise.
 
just getting back from my busy life. Does anyone have a 2004 260da with the 350 mag with 2.20:1 ratio and 20pitch cupped props or is it a different setup. If so they should be having the same problems I am. I am now told I can try 20 pitch uncupped props.
 
Sounds to me like the boat/engine package is simply borderline underpowered/undergeared.
Those 20 inch BIII props are notoriously inefficient. You will almost never see them on a new
boat these days. Even the 22's are not much better. Baring an engine HP or tach inaccuracy
problem the only thing that will get you up to 4800 - 5000 rpm is a gear change to the 2.43.
Hopefully that change will also allow going to the 22's. Even if after changing gear ratio you
still have to use the 20's the boat will perform better overall, and you could maybe add some
additional cup to the 20's. Have also tried two props of different pitch on the BIII's but wasn't much difference from two of the same pitch.
 
This is just a idea. Take boat out. Trim tabs full up motor full trim tab down. Take throttle to max power. As boat planes trim motor up to attain max rpm. Should be near wot. IF not take service manager for a ride. I am not real smart on this stuff, but start with the basics and work from there. Hope this helps some.

Good Luck,

KD
 
Sounds to me like a bad tach and under pitched. Get a shop tach connected while you're running to check against boat tach.
 
Also something else to check is to see if the throttle is actually going to full throttle. You could have a throttle cable out of adjustment or something binding up.

Good Luck,

KD
 
I had similar problems. Changed the ratio and you would never know it's the same boat. I tried different props, trims etc.
 
You may not have a way to judge against, but how quickly does you boat accelerate?

And according to Andy, the ratio change may very well be the answer. I would say it's a Mfg's problem but what do I know.
 
quote:
Originally posted by krb260

just getting back from my busy life. Does anyone have a 2004 260da with the 350 mag with 2.20:1 ratio and 20pitch cupped props or is it a different setup. If so they should be having the same problems I am. I am now told I can try 20 pitch uncupped props.

Click to expand...


I've got a 350 Mag, B3 2.20:1 with 28 pitch wheels. 5000 rpms wot.

20" cupped is 22" uncupped.
 
Just to add to my earlier comments. My boat is similar in size, different manufacturer, different power, however my problems were very similar. I spent my first summer, changing props (pitch, size, blades) trying to get my WOT and cruising rpm's where they were supposed to be. My WOT wasn't bad, but my rpm's were 3800 - 4000 to keep it on plane no matter what I did with my tabs and trim. I was using twice as much gas as anybody else and my dealer wasn't much assistance. I finally demanded a gear change and with minimal cost, my dealer agreed. The following summer, was like a I had a different boat. My fuel consumption was half and I cruised nicely at 3200 rpm and 27 mph gps. Very satisfied now!!!
 
Do you keep the boat on a trailer? If so do you take the boat off the trailer or run with it? Trailers still hooked up while running create enormous drag!

Sorry folks, I just had to..........

Correctly propping a boat can be a huge p.i.t.a!!! But this gentleman bought a brand new boat with a brand new drive, & brand new props! sounds like the props have been checked & re-checked! I would be on the horn with Sea Ray chewing their ear off. I would also be in the dealership's manager's or owners office with this! Ask to talk with someone who wears a tie! This boat is not set up right & never has been. He shouldn't be killing himself trying to figure out what was never right from shove off.
Tell the dealership that they can pound sand if they think that you'll buy from them again or Sea Ray for that matter if they don't get it right...........

THERE...now I feel better............
 
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