Prop blowout

[teecro]

Strangest thing happened today running the toon with just me and the wife at normal WOT and just a little trim; actually just a little less than I recall using last year. This I figured might be due to a lot of growth on the toons. Anyway we are running along and out of the blue we experienced prop blowout, this pretty much continued trimmed all the way down and would only stop if we reduced RPM to roughly 4K. Finding nothing wrong with the prop we went to the closest marina and topped off the fuel as I knew we were down to at best 5 gallons. Well 27.5 gallons later and no more blowout from the prop. I find it odd that the boat would be so fussy but least it was an easy fix....

[Bamaman]

It's been known to happen when I get a small log caught on the front of the lower unit. I'll back up and see the sticks or log float out of the tunnel (at the front.)

Then kick it in gear and go back to running normal.

When running a pontoon, you've got to watch what's in front of you constantly. Anything in front funnels to the motor. A v hull boat is a different animal as anything you hit usually gets thrown to the side and away from the outdrive.

[grouser]

I agree the smallest thing can cause this,,,

[teecro]

Wasn't debris that I'm sure of as I did raise the motor clear of the water as well as reversed the motor more than once too.... So I'm just going to file it away and see if it returns next time I'm low on gas...

[Bryden24shp]

Hey T, that's an outboard on the back, right? Could you drop it a hole or two on the transom? The weight loss from the fuel being burnt may be enough to raise the stern enough for the prop to ventilate. something to try...

[rhorne]

I had a Crest that did the exact same thing. Get low on fuel and every one sitting up front it would have cavitation. You can lower the motor one hole, keep gas tank full or have some passengers move to the rear. Any of those should solve your problem.

[Tlowry]

Does your motor pod have a 'V' on the bottom at the very back right before the anti cavitation plate? Mine did and blow-out was a big problem until I cut it off. Now the motor has a good bite and trim is much more effective no matter fuel load or passenger placement. And i didn't have to drop it a hole either.

[teecro]

Does your motor pod have a 'V' on the bottom at the very back right before the anti cavitation plate? Mine did and blow-out was a big problem until I cut it off. Now the motor has a good bite and trim is much more effective no matter fuel load or passenger placement. And i didn't have to drop it a hole either.

It sure does; took the boat out of the water yesterday to build a tow bar and power wash the pontoons and I sure looked at that part and thought what the hell purpose did it serve... I may have to pull out again tomorrow and get ride of that V piece as I can't lower the motor any lower than it is... THANKS!!!

[teecro]

I had a Crest that did the exact same thing. Get low on fuel and every one sitting up front it would have cavitation. You can lower the motor one hole, keep gas tank full or have some passengers move to the rear. Any of those should solve your problem.

Was just the wife and me and when it first blew out she was up front but it continued even with her sitting in the back till we gassed up.....

[Bamaman]

Come to think about it, my old Starcraft would ventilate when a couple of people sat in the very front. Raised my prop slightly. Sometimes it just takes an inch or so difference to get the blowout. I'd have to ask everyone to sit in back.

My Bennie's not like that, thank goodness.

[Capt. Dan]

Our Bennington did that, small boats are all sensotive to loading and trim.

[Tlowry]

It sure does; took the boat out of the water yesterday to build a tow bar and power wash the pontoons and I sure looked at that part and thought what the hell purpose did it serve... I may have to pull out again tomorrow and get ride of that V piece as I can't lower the motor any lower than it is... THANKS!!!

I was in Bass pro to buy come gear and ran into the salesman that sold me the boat. He asked asked how it was on top end and I told him the story of the V-sectomy and how it improved the situation. He said he had heard of this being a problem and some owners trim the V, said it was a splash deflector and went on to say the LU of the 14 Mercs was redesigned (I haven't verified that one) which changed the flow. After removing it, I see no splash-back issues at all and can run 1/4 up trim with no blowout which changes the speed from 25 to 30mph with me, the Mrs, a 1/2 tank of fuel and gear.

[teecro]

Well the V thingie is gone.... Report later....

[teecro]

Ok so the wife and I got the boat out this afternoon for a beer cruise and while cutting off the V bracket sure seems to have made the trim much more effective and allowed at least another 200 RPM... The bow sure seems to hold out the water a bit higher. I can't report any speed difference as I forgot my phone at home but the boat does feel faster. Now on the downside there is a lot more water splashing/boiling up around the motor....

[Tlowry]

Maybe a splash plate on the bottom of the transom would cure that.