twin 100hp engines on a 23 foot boat? - The Hull Truth

demolition_x · 04-26-2006, 01:57 AM

how would it run?

boat would be between 3500-4500.

would it be a total dog?

just curious.

Deanster · 04-26-2006, 02:23 AM

Nope - probably run pretty nicely. I had a 22' Boston Whaler Outrage with twin 1994 Merc 115's, which is probably a 1:1 equivalent with a modern 100, and that was a great boat. Right on 4000lbs with fuel, 2pax, and normal gear. Not super fast at the top end, in part because the previous owner had High Five 5-blade props on both motors, which gave monster hole shot, but a little pokey at the top end - it maxed at 40 mph.

Excellent reliability, but it wouldn't plane on one engine with anything like a full load. Great maneuverability, too.

All that said, twin 100's are vastly more expensive than a single 200, heavier, more drag in the water, more fuel, cost more to rig, maintain, etc. The current generation of big DI 2-strokes and 4-strokes have made rigs with twin smaller engines uncommon, if not exactly obsolete.

Unless having a twin-engine configuration is critical to your application, current conventional wisdom (and simple pocketbook math) points in the direction of a single larger outboard.

But twin 100's on a 4000lb mid-sized boat isn't a dog - it can be an awesome configuration, just not an especially price-efficient one.

Dae · 04-26-2006, 02:49 AM

I might not be a dog, but it's not worth it. If not due to cost, it's due to it acting like you had a 175hp single because the extra weight and extra drag in the water. You'd be better off with a single 200 or better yet, a 225. Look at what the max hp for the hull is and don't go less then 75% of the rating.

- Dae

demolition_x · 04-26-2006, 02:52 AM

well they are used engines old at late 80's. great shape low hours but cheap.

im just seeing what can be done. i want to make a full transom and mount twins or a big single.

Top_Cat · 04-26-2006, 03:02 AM

A decent engine package for a 23 footer woud be single 250 or twin 150's. A setup like that will most probably cruise at 31 to 34 mph at 4000 rpm.
Personally, I would not touch twin 100's or twin 115's for that matter.

demolition_x · 04-26-2006, 03:32 AM

yea i know. just trying not to spend alot for this little project im gonna have going.

i will probably end up with a single 225 or 250 unless i can find a set of twins.

Drifter · 04-26-2006, 05:38 AM

It should depend on the application (such as how far offshore you plan to go on a regular basis).

bmaster · 04-26-2006, 06:45 AM

i always wonder how people come up with this extra drag, slower speed for twins info?i used to think that was true, but 3 years ago i bought a 23 mako that i repowered with twin 115 dfi evinrudes.great hole shot, 43mph wot with avg load.my good friend fell in love with my boat, went out and got the same yr, model size mako but with a single 225.perfomance wise i have better time to plane, and same top speed, not slower from extra drag or wieght.becouse i have 8 pistons ( 2 4cyl) pushing the boat instead of 6 you can easily feel the extra torque.yes, twins do cost more as i could repowered with a single for about 1k$ less, but i like the extra manuverability in close spaces.the only advantage my buddys boat has is when its choppy, my transom dips down a bit lower than his from the extra 200 lbs.

1Bigtrouble · 04-26-2006, 08:21 AM

I beg to disagree, just bought a 2006 23 Parker with single 225 Yami, so far its getting avrage 3.5 to 4 mpg at cruise. twin 115 or 150's, even single 250, can't possibly get similar milage.

Tunahelper · 04-26-2006, 01:54 PM

I had twin 1990 115's on my Sea Ray Laguna 23. It is probably a little bigger than what you are looking at, but I can give you some numbers to consider. The weight is around 4650# empty, actual length is 24 ft. It burned something like 17 gph at 29mph in the bay with a light load and 18 gph at 27 mph going offshore with a heavy load. Top speed was low to mid 30's mph. It wasn't bad with a light load (2 or 3 guys and 60 gal gas). Offshore with a heavy load (4 guys, 130 gal gas) it was slow to plane and really bogged down in bigger seas.

2 years ago I repowered with twin 135 Optimax's. Now I can run offshore with 4 guys and 130 gal gas at 28mph burning about 13gph, top end is low to mid 40's.

demolition_x · 04-26-2006, 03:21 PM

thanks for all the info.

i have to see whats around first.

i like twins just for peace of mind when im off shore.

but a single might be the best way for now.

Capt Stan · 04-26-2006, 04:28 PM

I have a 23 ft with twin 115 4 stroke yammies. I believe my hull weight is right about 4500 lbs. Fully loaded with fuel (110 gal) and loaded for fishing with 3 guys I can get 42 MPH on the GPS out of her. She cruises nice at about 4500 to 4800 rpms and will be right at 30 MPH Gps. I'm happy with her. I think you'll be good to go if your not worrried about being a speed demon.