Originalronza

I've decided the twin bbc are the way for me to go on the 306 cat, I want to have the ability to run 130 plus when I need it and cruise at 100mph for long durations. The merc 525 or the ilmors will do that

Pismo10

single, if I lived on a lake and twins if I lived on the Ocean.

audacity

not trying to step on your dream boat...just a few things to think about. not sure if u have been taking to the company....but 130 with 525's is right at the world kilo record. and for a much narrower hull than a DW or skater outboard boat. not sure if u r talking closed or open boat? for easy math 100 mph at wot with 100 gallons is 1 hour. not sure what tanks u will have? range and weight distribution will b an issue if u plan on doing some poker runs and running offshore. going with Ilmore 625's is cool...great company and people to work with!!! but i would be shocked if any 30' cat had room for correct shaft geometry! more so on a narrow beam cat.
if you're open to input and buying/building a new boat of this size; peter at skater has forgotten more than most manufacturers collectively have. this is why many manufacturers have had peter build their prototypes and or race hulls. doug wright should also b on that call list too.
cheers mate
merry x-mas
and good luck with the project!!

WILDMAN

I run twin 300XS motors. Run them wide open forever without worrying about blowing them up. Two outboards weigh 200 lbs less than one I/O.


http://www.offshoreonly.com/classifi...o38922-en.html

Uncle Dave

mmmm I think power to weight is very close or slightly in favor of the single I/O.

Merc 300sx's are about 505 lb each short shaft version

I like Whackers for sure, but extended salt running just wipes them out over time whereas the closed loop inboards will go through exhausts, but enjoy longer lifespans.

Vs My setup

Transom Assembly weight about 100
XR assembly about 150
(taken from nascat thread)
Ilmor 710 -about 800LB

about 1050 and 700 ponies. 1.5 lb / hp

Vs twin OB"s @ 1010 and 600 ponies. 1.75 lb per hp

These ilmor mills run flat out for hours as well.



Uncle Dave

audacity

What a rock n pleasure boat! nice minimal cabin in a 100 mph, reliable offshore.

X-Rated30

One more plus for the twin OBs. Almost triple the range for the same fuel. And you can still go 100.

audacity

I read in powerboat magazine once: "it's not how fast you go; it's how well you go fast"

cougarcat

Another vote for the twin o/b's. I've owned the same boat both ways (26 Daytona-- one 2001 single, one 2005 with o/b's). 2001 with warmed up Merc 575---89.9. 2005 twin 300x's---112.6. Solid reliability and performance.

The o/b boat will run 36-37 with one engine offline
Sterndrive boat........ and you're paddling

seafordguy

I figured "Hell, I can't afford to run either, so why not go for twins"