Hole shot blow out...

[ASCTLC]

Is it unrealistic to believe I should be able to just hammer the throttle from a dead stop and not blow out (without being over propped)? My Suz DF115 and 17' Lund Angler requires an easy throttle to get the boat going or it'll blow out bad. Same for anywhere in the throttle range. (only 30 hours on the engine and not a scratch on the prop so highly doubt I have a spun prop).

I believe this is due to being severely under propped (hit 6300 rev limiter w/ only 80% physical throttle), but thought I saw another post of someone stating they were properly propped (via proper upper RPM range) yet couldn't just hammer the trottle without blowing out.

Thanks,
Andy

 

[Texasmark]

Re: Hole shot blow out...

Blow out means that the prop can suck air rather than water so it is either not designed for high performance or mounted/raised (trimed) too high...simple as that.

Cupping helps to prevent it.

Slowly advancing the throttle as the boat picks up speed, rather than firewalling it helps.

Lowering the engine all the way helps prevent it. (tuck it in)

Having the antivcav plate slightly above the bottom of the boat (vs higher) helps prevent it.

A low pitched prop on a heavy to get out hull might cause it. Says the engine could spin up for not much headway, creating a vacuum which could suck in air. Yeah, I'd go for that.

Different setups/equip will allow you to do different things. What someone else does may or may not be possible with your rig.....all different as are operating circumstances.

I agree with you on your underpropped statement.

The current boat I have was 2 yrs old when purchased. Owner had a 17P prop on it. First hole shot I got whiplash. To get it right I had to go to a 24P. Now, was I under propped or not? Grin. Couldn't believe the guy ran that way for that long. Don't want to know what kind of rpm's he ran. This engine has no overrev limiter.

Mark

 

[ASCTLC]

Re: Hole shot blow out...

Thanks Mark. The anti-vent plate is just even with the bottom of the boat and there's no trimming position that will prevent this from happening. The "low pitched prop on a heavy to get out hull..." is just what I believe is the whole problem with the 15p prop on now. Just trying to get a realistic expectation when I change props if I still might experience blow out problems when all is set up right and trimmed properly.

Andy

 

[walleyehed]

Re: Hole shot blow out...

Is there any device, such as a transducer, speedwheel, etc, mounted with-in 12-14" of the center-line of the hull?

 

[ASCTLC]

Re: Hole shot blow out...

Actually, I think it might be. I'll be heading to storage tomorrow and will find out.

Andy

Is there any device, such as a transducer, speedwheel, etc, mounted with-in 12-14" of the center-line of the hull?

 

[ASCTLC]

Re: Hole shot blow out...

OK, the transducer is 12 1/2" from the center line. I have enough room to move it out to about 16"+ away. I'll give that a try.

Also, I went and actually measured, instead of eyeballed, the bottom of the boat to the floor and got 18 1/2" and the antivent plate is 17 1/2" from the floor. So I'm about an inch too low.

Andy