Moving center of gravity

[G DANE]

I read in a thread KennyB referring to a great advantage from adding a jackplate with 6" set-back. I am about to go ahead building my 17' runabout and would like to reach a good setup with my 115 Evin. I have the possibility of building a 10 gal tank in the rear between the mid stringers, as there are only two in rear. This would move center of gravity back, maybe similar to getting some set-back. Is the benefit from distributing weight back - or from what ?<br /><br />Will placing as much weight in back of boat gain speed ? The hull is a 17', 6,5 Beam ind the middle, 5,5' at transom.

 

[18rabbit]

Re: Moving center of gravity

G Dane – Just a thought; I run a 115 Johnson on an 18-ft Avon RIB. 10-gals would not get us through a day. I have a 20-gal tank installed forward, just ahead of the console, because that’s where the best fit is for this boat. Unless you know the smaller tank is what you need/want, you might want to query others here with more o/b experience (then me) about the size of your fuel tank. Smaller tank=less weight=faster boat???

 

[G DANE]

Re: Moving center of gravity

18 rabbit you are right - i just miscalculated from liter to usg. I ment 20 gallons. Would this weight right in front of transom act like a jackplate with set-back would on boat balance and speed.

 

[neumanns]

Re: Moving center of gravity

I think the better proformance is gained by the prop running in clean water and not as much by the weight set back. Better wait and see what the pro's say though.

 

[JasonJ]

Re: Moving center of gravity

This will depend on what your current running attitude is. If you can get the boat to run on the aft 1/3rd of the hull, you'll be in good shape. All my fuel is right at the back of my boat, on each side of the splashwell. I wouldn't have minded having a belly tank forward under the floor, but it wasn't in the budget. I just built the center console heavier and moved the battery forward and that helped with running attitude. I just mounted a bow mount Minn-kota with foot controls, and the battery will go under the right bow seat. My attitude should still be good, I was still running a bit high in the bow at planing speed...Heck, when the better half would sit up in the bow seat, the running attitude was still good, and she weighs a little bit more than a battery and a bow-mount....

 

[G DANE]

Re: Moving center of gravity

I guess I will have to wait and see, then. My boat was never in the water. It was bought as naked hull and uppersection, from factory, by a guy who wanted this special hull shape, and would convert it to centerconsole. He divorced and never finished it, sold it again to another guy who did the same ( se a pattern in rebuilding boats ? ) Now I am working on it, bringing it back to original look. Its from 1996, but I drilled the first holes for a motor in it. ( havnt divorced yet ) Hope to get it finished this spring, had to take a break rebuilding kitchen this summer.

 

[G DANE]

Re: Moving center of gravity

Thanks for your replies - I new in working on glassfiberboats, in this way at least.

 

[walleyehed]

Re: Moving center of gravity

G.Dane, I've got a 62" M.K. on the bow-74lb., 24vlt. with both group 31's under the step between the consoles. I also incorporated a 32gal livewell up front. In the rear (of the boat ), I've got 24 gal fuel, and the starter batt., which is a group 27. <br />Each boat is going to be alittle different, and if you find your boat has some attitude problems, I think I can talk you through the transom extensions with very minumal effort required on your part.<br />If I could make one recommendation while you are setting up your rig, it would be to make your batt cables from the engine to batt. about 2ft. longer than you think you will need....that way you will have room to move back some if needed, without worrying about length.

 

[G DANE]

Re: Moving center of gravity

Thanks<br /><br />I got lots of battery cable, I just worked a place they build an internetserver site. They dumped lots of yards of low volt cables thick as a littlefinger, in pieces 10 - 15 yrds. I saved some. I guess I should be carefull not to get all weight back then. Thanks.