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Random Thoughts on Triple Engine Boats

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Old 12-23-2010, 11:50 AM
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Default Random Thoughts on Triple Engine Boats

What is your opinion of taking a triple engine boat and removing the center engine and driveline and reglassing the hole in the transom.

If the tripples gave a top end of 75, would the twin version (with new props) reach 60? Leaving the remaining two engines exactly where they are in the back of the boat.

I fully understand that to do this properly, you would want to remove all three, reglass the transom, and then install higher HP twins on close stagger. But, if you could get a tripple at the right price, you would also result in a spare engine and drive as part of the deal.
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Old 12-23-2010, 12:41 PM
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Leaving the 2 remaining engines in the same place in the boat would likely wreak havoc on your CG.
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Old 12-23-2010, 01:14 PM
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What model would only run 75 with trips?
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Old 12-23-2010, 01:32 PM
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What model would only run 75 with trips?
Was just throwing out a number, real numbers could be all over the place depending upon model, individual engine ratings, Ex. a BT with trip 415's may not be so fast.
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Old 12-23-2010, 01:35 PM
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Originally Posted by 88Fount33 View Post
What is your opinion of taking a triple engine boat and removing the center engine and driveline and reglassing the hole in the transom.

If the tripples gave a top end of 75, would the twin version (with new props) reach 60? Leaving the remaining two engines exactly where they are in the back of the boat.

I fully understand that to do this properly, you would want to remove all three, reglass the transom, and then install higher HP twins on close stagger. But, if you could get a tripple at the right price, you would also result in a spare engine and drive as part of the deal.
About 9 years ago I actually did that on a temporary basis with my first 50 NT. I blew up the center motor and was bound and bent to keep on boating so had the engine and drive pulled and put a gasketed blank plate on the transom assembly. I ran with the port and starboard engines only. Think I was down about 15 mph from my top end of about 85 mph. Boat felt much lighter but was happy to get that center engine rebuilt and back in the boat. The center of gravity would definitely be a concern on a smaller lighter boat I am sure. You could try that before you did any glass work to see how it performs. Good luck.
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Old 12-23-2010, 01:47 PM
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I have to kind of question the COG think. Aren't most big tripples built as twins as well? I guess it would depend on what boat. Im sure it would affect it but nothing that couldn't be" tuned"
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Old 12-23-2010, 04:28 PM
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About 9 years ago I actually did that on a temporary basis with my first 50 NT. I blew up the center motor and was bound and bent to keep on boating so had the engine and drive pulled and put a gasketed blank plate on the transom assembly. I ran with the port and starboard engines only. Think I was down about 15 mph from my top end of about 85 mph. Boat felt much lighter but was happy to get that center engine rebuilt and back in the boat. The center of gravity would definitely be a concern on a smaller lighter boat I am sure. You could try that before you did any glass work to see how it performs. Good luck.
Bob
Of course, Bob has already done it and a LONG time ago as well!!!!

Did it turn OK? Did the time to plane double or tripple? If it was a Bravo boat, bet they just LOVED that added stress.
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Old 12-23-2010, 04:46 PM
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I can't speak for any other mfr. but OL tripple engine boats are designed with a specific cg. if you removed the third engine you would have a cg issue that would need to be adressed, it could be done, but is the juice worth the squeeze? buy a nice twin and be done with it.
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Old 12-23-2010, 04:55 PM
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We have triples on a 48'er Sunseeker with 502MAG's and bravo drives. Never had a drive failure but tons of engine issues.....and I dont' think it's the boat's fault even though it is over 19,000lbs. I've had a engine issue and had to run on two and can still get up on plane. It's been proven a few times!

Since June we have been rebuilding all three drives, all three motors, bottom paint and next is a dash/electronics redo before spring. Somebody will get a nice boat next year!

I would image that that the center of gravity (COG) would be affected quite a bit if you removed an engine.
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Old 12-23-2010, 05:21 PM
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Of course, Bob has already done it and a LONG time ago as well!!!!

Did it turn OK? Did the time to plane double or tripple? If it was a Bravo boat, bet they just LOVED that added stress.
He, he. Boat turned fine, no issue there. I cannot remember time to plane etc but agree it would take longer to get up and running if I had full fuel and a load of passengers. And yes that boat was a drive eater.
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