Balance point on monos?

[mark voorhies]

O.K. Guys, I checked the Speedmaster first- 11" or 29.5%(tanks empty-17Oz.) The A.C. Lazer 40" 12.5" or 31% with a empty 24 Oz. tank-maybe I should move the Rs 45 into one of the 39 or40" hulls :blink: .

Thanks for your replies,

Glenn

Glenn, you weren't still waiting for a reply on this - were you? If you are: Speedmaster = 11.02" @ 29% / Lazer sounds correct , but for a 40" boat should put it at about 11.6" - However; you have a .67 motor in that one, so 12.5" put's it at the high side. I noticed that you have a pretty good sized tank for the .45. I ran a 16oz. in mine, and that's when the cg. was hard to control - making it do (Front Dig) in the corner, until I burned the fuel-off. Also, I'd have alot of fuel left over after the race. Try a 10oz. and see how that goes. Put the CG at 29% Dry tank or 31-32% when the take is full. This way when the fuel burns, the CG will move back - hopefully to within 29%.. If your hull is digging in the corners(Bow down/Stern up) your CG may be off or your strut may have too much neg. angle. Check your trim tabs too.. (Bow up or flipping over) is the reverse of this. Also, one more point to add is the Manufac. instructions are just a guide line for the hull for CG. Always do a manual check of this to find the true CG of your boat.. Do the 2 index finger test/find the balancing point - then measure forward from the transom to find the length. Take the overall length of the hull and X's that by the measurement that you just took. Don't forget to do the % sign. This should give you a true measurement of where your at. It should fall around(i.e. 11.02 Speedmaster boat).

Sorry, maybe you know all this already - just trying to help. Go with smaller tanks if you can.

Thanks Ted, Boats are not digging in corners- both are fast and perhaps too light. I'll play with the struts a little next year(neither have much movement but I can tilt them a little). Also going to try adding weight(inside the noodles) that I can adjust fore and aft. May also look into some different props- I ran a x646/3 on the 45 and a x457/3 on the 67(@4200 ft. elevation).

Thanks,

Glenn

Glenn,

Noticed your elevation, thats goin to keep you down on HP, your prop choices will be smaller for sure to most you read about. My elevation is about 900 ft. and run x460 to x462 on a .67 CMB in a mono. I have run 32% up to 35% on balance point on a heat race mono hull with good results. I always figure this with an empty fuel cell,

full tank of fuel helps get the hull through the ruff water at the start of a race and then moves CG back as tank empties to really let the boat use the HP.

 

[Glenn Gates]

O.K. Guys, I checked the Speedmaster first- 11" or 29.5%(tanks empty-17Oz.) The A.C. Lazer 40" 12.5" or 31% with a empty 24 Oz. tank-maybe I should move the Rs 45 into one of the 39 or40" hulls :blink: .

Thanks for your replies,

Glenn

Glenn, you weren't still waiting for a reply on this - were you? If you are: Speedmaster = 11.02" @ 29% / Lazer sounds correct , but for a 40" boat should put it at about 11.6" - However; you have a .67 motor in that one, so 12.5" put's it at the high side. I noticed that you have a pretty good sized tank for the .45. I ran a 16oz. in mine, and that's when the cg. was hard to control - making it do (Front Dig) in the corner, until I burned the fuel-off. Also, I'd have alot of fuel left over after the race. Try a 10oz. and see how that goes. Put the CG at 29% Dry tank or 31-32% when the take is full. This way when the fuel burns, the CG will move back - hopefully to within 29%.. If your hull is digging in the corners(Bow down/Stern up) your CG may be off or your strut may have too much neg. angle. Check your trim tabs too.. (Bow up or flipping over) is the reverse of this. Also, one more point to add is the Manufac. instructions are just a guide line for the hull for CG. Always do a manual check of this to find the true CG of your boat.. Do the 2 index finger test/find the balancing point - then measure forward from the transom to find the length. Take the overall length of the hull and X's that by the measurement that you just took. Don't forget to do the % sign. This should give you a true measurement of where your at. It should fall around(i.e. 11.02 Speedmaster boat).

Sorry, maybe you know all this already - just trying to help. Go with smaller tanks if you can.

Thanks Ted, Boats are not digging in corners- both are fast and perhaps too light. I'll play with the struts a little next year(neither have much movement but I can tilt them a little). Also going to try adding weight(inside the noodles) that I can adjust fore and aft. May also look into some different props- I ran a x646/3 on the 45 and a x457/3 on the 67(@4200 ft. elevation).

Thanks,

Glenn

Glenn,

Noticed your elevation, thats goin to keep you down on HP, your prop choices will be smaller for sure to most you read about. My elevation is about 900 ft. and run x460 to x462 on a .67 CMB in a mono. I have run 32% up to 35% on balance point on a heat race mono hull with good results. I always figure this with an empty fuel cell,

full tank of fuel helps get the hull through the ruff water at the start of a race and then moves CG back as tank empties to really let the boat use the HP.

HP not a problem. Think I need to tighten boats up a bit to handle race water. Prop for the 45- X646/3. 67- X457/3. Wouldn't hurt to add weight to front to move CG Fwd. I think David Wilfong is running around 35% on his Cal-Craft 45. A bit more throttle management wouldn't hurt either.

Thanks,

Glenn