Top speed variables..

Nick70

Active Member
Apr 20, 2016
206
New England
Boat Info
2006 Searay 260 DA 496 mag
RAYMARINE stuff.
Engines
496 Magnum
Bravo III
Boat: 2006 Sundancer 260 with 496/Bravo III
Conditions: 12mph winds, 1-2ft seas, full camper top on boat.
Result: 40 mph @ 5000 rpm.
I was a little surprised to see that low of a number but it was a bit snotty and the camper enclosure was up.
I’m thinking, since the boat/engine got all it’s power band, everything seems fine.
How much do you think the conditions could effect the top speed number?
I will also add, the dealer test drove it and I believe he said he has the drive trimmed almost all the way up..which didn’t make a ton of sense to me..when I had my 260/350 mag all it needed was a shot of up trim..to much and it would porpoise.
All boats are different as are captains I guess...
Anyway, I was hoping to see a number more in line with the power upgrade from what I was used to with the 350...I had a top speed of about 38.
I’m thinking the 496 in calm seas, should get mid to upper 40’s...
Could chop, wind and the resistance of the camper top be enough to slow it that much?
 
IMG_4230.JPG
How did you you measure the speed? Speedometer in boat, GPS, radar gun?
 
I had a 2003 280 DA with 496 Mag and it was a 44mph boat all day long.
 
Conditions like chop, wind, and your camper top like you described will effect top speed on your boat, but probably not by more than a couple of knots.
Example: I was out Sunday in a chop and 20 mph average wind speed. White caps breaking on the bay. Both were out of the east which is never a good thing around here. Heading east directly into it I probably lost a knot or so.
I’ve got the torque of the diesels, but your gas big block shouldn’t lose much more than that.
If that engine combo in that boat should be getting mid 40’s , and if your bottom is clean, the next place to look would probably be the prop.
Lot’s of guys opt for a pitch that will give them a better hole shot in exchange for a little off of top speed.
 
How clean / smooth is the bottom? Chunky bottom paint cost me 6-7 mph.

How much weight on the boat? My in-laws 97 270 DA usually tops at 33 mph. After a repair and having NOTHING in the boat (no canvas, cushions, toys, water, little fuel, etc) he hit 40+ mph.

I have the same hull. Having the trim all the way up in those conditions will not give you optimal speed and will likely cause pounding. About 1/2 to 2/3 would be optimal.
 
Yeah, assuming a stock prop in good shape, and the bottom is freshly painted, I’m thinking the drive being trimmed all the way up really held it back. He actually had it so far up while WOT, that the alarm tone sounded until he tapped it back down a bit.
The mystery that remains is WHY? Why would anyone trim the drive all the way up like that while WOT and making a video for a prospective buyer.
Weird.
 
Boat: 2006 Sundancer 260 with 496/Bravo III
Conditions: 12mph winds, 1-2ft seas, full camper top on boat.
Result: 40 mph @ 5000 rpm.
I was a little surprised to see that low of a number but it was a bit snotty and the camper enclosure was up.
I’m thinking, since the boat/engine got all it’s power band, everything seems fine.
How much do you think the conditions could effect the top speed number?
I will also add, the dealer test drove it and I believe he said he has the drive trimmed almost all the way up..which didn’t make a ton of sense to me..when I had my 260/350 mag all it needed was a shot of up trim..to much and it would porpoise.
All boats are different as are captains I guess...
Anyway, I was hoping to see a number more in line with the power upgrade from what I was used to with the 350...I had a top speed of about 38.
I’m thinking the 496 in calm seas, should get mid to upper 40’s...
Could chop, wind and the resistance of the camper top be enough to slow it that much?
Realistic top speed I'd say would be in the 43-47mph range when things are favorable. As far as trim I wouldn't ponder the 'why' of the dealers test too much. All I know from the boats that I've had are they are all the same. While going WOT trim the drive up in 'taps' until you start to lose speed then 'tap' it back down...that's as fast as it'll go that day, with clean/dirty hull, with that load, with the canvas up/down, in those wind/sea conditions.

That correct amount of trim can vary some along with the other things.
 
Clean bottom, no wind, no current, you should hit 45 mph not 45 knots. I hit 50 mph once in my 280DA with brand new bottom paint and the full camper top on. I have wondered since if the camper top is more aerodynamic than no canvas. Does running the small bimini only creat more low pressure drag behind the wind shield than the full camper top?
 
I had a 2003 280 DA with 496 Mag and it was a 44mph boat all day long.
How did you like that boat overall?
I may consider a 05-07 280/496 mag vs another 260.
Any thoughts much appreciated.
 
Clean bottom, no wind, no current, you should hit 45 mph not 45 knots. I hit 50 mph once in my 280DA with brand new bottom paint and the full camper top on. I have wondered since if the camper top is more aerodynamic than no canvas. Does running the small bimini only creat more low pressure drag behind the wind shield than the full camper top?
What year 280?
That’s so WEIRD! The 260 only topped at 40..and it got to 5k rpm too , running 28 pitch props..mystery. Almost makes me consider not getting that boat.
 
What year 280?
That’s so WEIRD! The 260 only topped at 40..and it got to 5k rpm too , running 28 pitch props..mystery. Almost makes me consider not getting that boat.
I don't think 28" is the correct prop pitch for that boat/drive combo. My guess is 24" pitch. You ought to double check the drive ratio on that boat.
 

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