How much will the C of G change?

[Gene H]

I have a 36 ft trawler with twin diesels. I'm changing transmissions and the new output shaft has a two inch drop from the old transmission ouput shaft centerline. This means I have to raise the engines two inches. Does anyone know if that is a minor adjustment or a major adjustment to the boats center of gravity. Obviously the longitudinal c/g goes up verticaly on the boat. Is two inches too much for a 36 ft long, 14 ft wide 10 ton boat?

[Raggi_Thor]

What's the weight of the two engines?
One ton?
Maybe the cg will rise 1/2 inch?
I don't think that is major.
It depends on the weight of the engines.

[Gene H]

They are turbo'd in line 6 cylinders so I have to believe they weigh around 1,200 to 1,400 lbs each.

[Laursen]

I agree it is good that you are thinking about this but a couple of inches either way is not going to affect anything also how much heavier are the transmissions that you are putting in over the orignals ?

Frank L

[Raggi_Thor]

The engines are maybe 15% of the total weight, so my guess is that two inches up isn't a major change.

[Gene H]

The new transmissions are about 100lbs which is about 33 lbs heavier than the old ones. The boat is nose heavy though so a little more weight behind the moment point is no problem.

[Laursen]

My concern would be to make sure you have enough holding the engines to the stringers cause the trans weight will and is going to help you. I think when putting the new engine mounts make sure you extend the mount down not the stringer up to the mount cause then I think you could have a problem and extend the mounting surface of the mount maybe an extra bolt so it has more surface area to transfer the pressure to

Just some food for thought

Frank