Ideeal point of balance

[G DANE]

This question is inspired by boatboys thread about tank placement.<br /><br />When i find the time to, I am rerigging a light 16' runabout with my evinrude 115, new seats,batteries, windshiels, hardware and tanks. The boat has a maximum with of 78", 67" at transum.<br /><br />Are there any rules of thump, where the piont of balance should be, i exa 1/3 of boat length measured from transum or similar to get a boat that handles as good as possible, and isnt potential to get unexpectedly "airborne", any time.

 

[deeep water]

Re: Ideeal point of balance

if you can get a sling under it you dont have to lift it very far to get close to your c/b,,from there you can add equip fwd or rear to plane

 

[G DANE]

Re: Ideeal point of balance

I know I can determine where it is, that way, is actually is less than 1/3 boat lenght from transom, but is there a rule of thump, where it should be, I still havnt got batteres in and windshield on. I will be using 2 or 3 6 gal portable tanks, all placed under rear benchseat.

 

[JasonJ]

Re: Ideeal point of balance

The only real way is to get it so it can be run, and experiment with weight placement under way. You might figure out a theoretical balance point only to find out it handles horribly. Trim, prop design, hull design, and weight placement are all factors, something that is hard to do without test running it in its most likely running conditions. I don't think a generic rule of thumb will get you were you want to be without experimentation. Good luck...

 

[Richard Petersen]

Re: Ideeal point of balance

Is your boat rated for a lesser hp? What is it?

 

[G DANE]

Re: Ideeal point of balance

Its rated for 85 HP, if i go by the USCG rules for backyard boatbuilders. Hull has no id plate.

 

[bigboy]

Re: Ideeal point of balance

I think i'm going to put my tank in the back. But my 17 foot is tared voor 150pk and i have 140 so it isn't overpowered at all!

 

[G DANE]

Re: Ideeal point of balance

No it isnt, and an Arrowbeau will easily handle 200 HP, I even know of one here in Denmark with a merc 225, they used for pulling parachutes, no problem. I would put tank in back, tank is not a permanent weight factor, I would prefer to move batteries up front if a have to balance, thats permanent. I dont think a V-hull will be airbourne easy, the ones you see fly on tv are hydros, they are build to be partially airbourne, I fear more that the bow gets lifted accidently when crosing wakes, and in chop.

 

[bigboy]

Re: Ideeal point of balance

Yes, i've heard that you may not place the battery more dan 1m50 from your engine. Otherwise you will loose to much force to start your engine. With heavy engines i mean... like 150 +

 

[G DANE]

Re: Ideeal point of balance

Thats a question of heavy cables, I've got 50 squarem.m. cables from a computersite. I will do some trial and error when I get it running next spring.

 

[bigboy]

Re: Ideeal point of balance

Originally posted by G DANE:<br /> Thats a question of heavy cables, I've got 50 squarem.m. cables from a computersite. I will do some trial and error when I get it running next spring.

Dont forget the weight and cost of long thick cables...

 

[G DANE]

Re: Ideeal point of balance

They would only weigh a couple of kgs or three, I think. I have plenty of cable, but dont know what it would cost to send you some. If you are interested, I can do a little invastigation, and see how much I have, I think I have more than I can use myselves. Your boat looks good, wish it was mine. Do you think you will be ready for spring ?

 

[G DANE]

Re: Ideeal point of balance

3 kgs to nederlanden would cost 26 euro