Bertram 28 top speed

WOT should be 4200 RPM....something is wrong....

Props not correct?

Bottom dirty?

Tune -up?

I would think one of the above (or any combo of all three)

Hope this helps...

Boat Speed

How long have you owned the boat? What was the speed or rpm before this? Has the boat been sitting for awhile without running. Definitely sounds like a dirty bottom or propped incorrectly.

Or a bad motor that's not putting out it's rated power.

A friend of mine put 240hp Yanmars in his 28' Bertram Bahia Mar (express), and it does 34 knots.

2000 rpms on both motors? Wrong props, bad bottom or bad fuel are most likely.

My Bertram 28 with 350ci Vortec 5.7 engines does 27 knots WOT ... 4000 rpm's. I'm going to try the stock props this summer and see what happens with the performance numbers. I cruise around 3200 rpm's and 22-24 knots.

Mike

Sounds right on target.

my 28 with 2 225 honda 4 stroke outboards and a bracket does 28 at 4000 RPMs and 41 at 5500 RPMs.

That sounds right. I've got twin Yamaha 250hp on mine and seeing the same sort of speeds. 40 knots is plain scary

Puf

Those are good numbers. I ran a 28 with Yanmar 185hp engines and it cruised at 20 knots and topped out around 25 knots. I think the Yanmar 220's would be the ideal engine for those boats......The 185's barely kept it on plane at 20 knots, you needed a lot of tabs otherwise they would only push it 16-17knots at cruise.

speed

It's not scary to me. I was a EVINRUDE test boat driver in the early 80's.I went 83 mph in a 20' ranger bass boat with a 300 GT V8 outboard.

Speaking of which, A friend of mine has a 20' ranger with a built up 250hp ocean pro and it does 92mph on gps. It starts getting a little scary after 75mph and start chine walking a little and stuff......

Mad...Quite mad!!

So is the owner. LOL

I know this is a old thread, but someone may find this information helpful regarding repowering there 28.

I have a 1981 Bertram 28 flybridge. It came factory with a pair of mercruiser 228 running alpha's. I repowered it 6 months ago with a pair of 5.7l vortec 280hp spec motors. The gimbals were replaced and new SEI standard and counter rotation outdrives fitted. The Alpha's are running 1.5 gear sets and props are Mercury 17" Rev4, it is currently a little over propped, looking at going back to 15's.

Anyway here are the numbers, Speed and fuel burn with full tanks, 44 gal water and 200gal fuel


1200rpm 6kn 6gal
2450rpm 16kn 14gal
2850rpm 19kn 16.3gal
2900rpm 21kn 17.2gal
3100rpm 22kn 19.5gal
3200rpm 23kn 20.3gal
3400rpm 25kn 26.9gal
4050rpm 34kn 42gal

If anyone has speed and fuel burn numbers for a 28 with outboards or diesels I would love to see them.

What is the pitch on the props that you have now?

Props are revolution 4's. Stainless steel 4 blade 14 5/8 diameter by 17 pitch

Is that fuel burn per hour or mile ?

Hello Sir, do you want me to remove your post..?