What are the signs / symptoms of too much setback

**hoodooguru** · 05-06-2011, 08:26 AM

As the title says.....signs / symptoms of a boat running too much setback?

**Riverman** · 05-06-2011, 08:37 AM

The boat sinks stern first.

The right amount of setback is when the boat flies nicely at full power with little positive trim. I suspect too much setback would result the boat feeling too flighty, difficulty getting on plane, etc.

**XstreamVking** · 05-06-2011, 09:29 AM

Too much set back will usually make a boat prone to porpoise at lower and mid range speeds. Also have to use neg. trim at top end to keep the bow dn. Can cause loss of speed at top end, and bad handling because of this... When boat is rite, as riverman said little or no trim is req. to fly the bow.... All about how you like the boat to run...

**specboatops** · 05-06-2011, 10:05 AM

Great thread....I need more setback. My bow rides very low at any trim angle...

**frederick55** · 05-06-2011, 10:12 AM

I have a Viking with a 225 looper, and I'm having the same issue now. I believe I have too much setback at 7". The boat planes fine because I'm running negative wedges, but at anything less than 55-60 mph, it popoises, and the ride is terrible. In addition I have to run sky high to get the prop out of the water and can't get my rpm's up inthe right range. It seems that the weight shift being further back causes a balance problem. Today I'm altering my jackplate to get as close to the transom as I can. I think if you have tank and battery in the stern, and add a heavy motor to that, you need to run closer to the transom, just my opinion. I'll let you know if I'm right after I make the change to the jackplate.

**XstreamVking** · 05-06-2011, 11:40 AM

After changing/moving parts and motors/plates around, I finally settled on a 2.5 efi merc, (best power to wt)with a 4" setback hyd. jackplate. Small oddesey battery in the bow.. Fuel against the transom. For my V-King this seems to be the best balance. Boat runs with level trim and will bring the bow up as more throttle is applied. I don't see it being better than that... 28p chopper, fairly stock motor and lwp lower, run even with the pad. About 86@7000r's... My boat is lite and the bottom is blueprinted flat.

**imq707s** · 05-06-2011, 12:04 PM

If your boat is wanting to fly the bow high at any speed...even with full negative trim, I would say that you have too much setback

**albypine** · 05-06-2011, 12:15 PM

subscribed.before my boat loved 14" of set back and now with all the wet foam finally out i may have to lose set back.

**specboatops** · 05-06-2011, 12:18 PM

Originally Posted by albypine

subscribed.before my boat loved 14" of set back and now with all the wet foam finally out i may have to lose set back.

Yep..... I can see that having a huge impact on it !

Chris

**baja200merk** · 05-06-2011, 12:25 PM

Completely depends on the boat!

**specboatops** · 05-06-2011, 12:29 PM

Originally Posted by baja200merk

Completely depends on the boat!

And the entended use to I assume.

**baja200merk** · 05-06-2011, 12:42 PM

Yes offshore too much setback will trash the ride/handling (unless the boat was designed for it). I have been told my t-1 runs better all around with setback, but its pretty flighty with 6in.

**hoodooguru** · 05-06-2011, 06:57 PM

Well I am starting to think my boat has too much setback at 6 inches. The stern has a rake on it anyway and when trimmed correctly the front of the bullet on the gearbox is 500 mm from the back of the pad. It's a 16 foot ski boat alot like an aussie bullet (flightcraft bandit hull).
I tested a new 14 x 28 yamaha drag prop by ron hill yesterday and had some weird issues. First try the propshaft was 2 inches below the pad and it ran 62mph @ 6100rpm on my 140hp looper (very healthy motor). Second run we lifted the motor an inch and it hit 60mph @5900 rpm. Third run we lowered it 3 inches below the pad and it did 67.9mph @ 6000rpm. Fourth run we lifted it up to 2.5 inches below the pad and it did 68.1mph @ 6000 rpm in very slow glass fresh water.
Obviously the motor can spin the prop without ease but it is ventilating / slipping when I try to trim it up more for speed. Obviously my motor can spin more than 6000rpm and it wants to but the prop starts to slip.
I think I'm going to take my 6 inch land and sea jacking plate off and try mounting the motor directly to the transome.
I was previously running an omc cleaver 14 x 27 pitch on it and it was VERY flighty, but it still did 70 mph @ 6200 rpm. The hull is clean and straight. Even before when I lifted the motor running the cleaver the rpm's would drop which I thought was weird. This boat should easily pull 75mph.