Huh...I posted from my phone but guess it did not go through. I will try again...

I have a 1986 27 Tournament with twin 2001 Merc 250 EFIs, 30 inch shafts on a Stainless Marine bracket set up for engines mounted 26 inches on center (it does not appear there is enough room for 28.5 inches on center). Top speed is 52-54 mph at 5700 rpms. Cruise is around 3100 rpms or so at 30 mph I think. Fuel consumption is high and based on some other performance tests I can find..cruise is around 20-25 gallons per hour and WOT is 50-59 gallons per hour. Part of me does not really want to know!

With the current engines, there is more than enough power. In fact, when you loaf around at cruise and then mash the throttles up to WOT, she pulls hard and you need to hold on. If I were to repower with less horsepower (i.e. twin Merc 150 4 strokes 3.0L with aftermarket extensions) I would obviously loose a fair amount of top speed (who regularly can go 50mph in the north atlantic anyway?) but based on BigShrimpin's performance of a single 150 on 23, would gain significant fuel economy. All very promising and intriguing but I don't want my boat to be a guinea pig so I would need to take a ride on another 27-28ft boat with those motors.

If money were no object, twin 300's would obviously be ALOT of fun and as KMOOSE experienced with the single 300 on his 23, the extra horsepower would most likely result in a very efficient cruise, because the engines are barely working.

Anyway, to answer the OP's question....the minimum horsepower may be twin Merc 3.0L 150's and in other brands perhaps twin 200's. Budget no concern? Go for twin 300's.

Happy to answer any other questions you may have.

I don't know, Tim. Pinder told me they're 5 or 6 years old, so go from that.

Those 250 EFI are strong, dependable motors but notoriously thirsty, especially under load. The 150s are fantastic motors and would likely push it ok on a nice day but would they have enough grunt to hold plane in steep swell at 18 knots or pull out of a trough in the inlet when your getting sucked into bottom of the wave behind you.

I already talked to him Tim but thank you for forwarding that link.

Obviously the Conch and my 27 are similar in size and weight but nothing like experiencing it first hand by going on a seatrial.

Ed - I saw your post in the last one, but I figured I would post it for everyone else. The new 225's are available in 30".

I'm not sure how bay manufacturing 5" extensions impact the warranties on the 150's (not that you'll need to warranty anything).

FWIW - I cruise at 4500rpm most of the time and that seems to be the happy place for my 150. Also he could gain a few MPH (200-300rpm) by running enertias rather than mirage's.


https://www.thehulltruth.com/parts-f...arranty-2.html

Very impressive numbers, Tim.

Thanks for sharing.

-Ed-