repowering 25 seafari????????

[seafari25]

Welcome Nuthinfancy,

I had a feeling there were a few more out there. The Seafari 25 is pretty fancy in my book.

I'm affraid I won't be of much help as I have the same questions as you. Good thing there are many members of CSC who are experts on these topics. I haven't really pushed this topic as my old 327 still turns the wheel(as of last October) but this is something I will have to think about down the line.

For years I have dreamed about repowering with twin outboards and I think she'd look great with a Hermco bracket and a pair of 250s(cant afford it ) but after some discussion with some of the experts and the info on this site, IMO, I feel it's best to repower with the same I\O setup. Extra space in the cockpit is nice but I'm more concerned with the boats performance. I am very pleased with the performance now(and the last 30 years) and would not want to experiment and be disappointed. Not to mention, the boat has a lot of sentimental value for me and I'd like to keep it as original as possible. I encourage you to dig up as much info on this site as you can before making your final decision as there are many factors that will make or break your project (ie: weight distribution etc..). There are many things that never entered my head before finding this site.

I am, however, interested to know what you decide so keep us informed and get some pics up. I'll be gawkin with Gillie.

Good luck,
Brandon

BTW Fr. Frank, great to hear your feedback on the diesel. I love the idea of a diesel for fuel consumption but I was just wondering if there would be any weight issues.

[Fr. Frank]

There is a weight penalty with the diesel. The weight of a 1970's Mercruiser small block Chevy/pre-alpha one setup is 1021 lbs. (New 350/300 MPI w/ Alpha One is 946 lbs)

Contrast that with the weight of the Cummins-Mercruiser 4.2L ES 320hp with Bravo One drive at 1201 lbs total.

The difference between the original setup and a new 320 hp diesel setup is 180 lbs.

FUEL CONSUMPTION COMPARISONS
However the 3900 rpm (WOT) fuel consumption of the diesel is 18.8 gph, and 75% power (3200 rpms) fuel consumption is 11.7 gph, and 60% power (2850 rpms) uses only 9.0 gph. Test boat was a '99 Bayliner 2855 SunBridge repowered in '06 with CMD.

WOT fuel consumption of the 2007 Mercruiser 350ci/310hp is 23.9gph at 5250 rpms WOT('07 SeaRay 26' 240 Sundancer) 75% power fuel consumption is 18.4 gph at 4800 rpms. (60% power at 4000 rpms setting drops you to 14.1 gph)

WOT Fuel consumption of a single Mercury 250 Optimax is 27.6 gph at 6000 rpms WOT. ('08 ProLine 23' CC). 75% Cruise fuel consumption is 13.9 gph @ 4800 rpms, and 60% power at 4500 rpms burns 11.6 gph. (remember to multiply this 2X-10% for twins)