Blowout at around 69mph.

[rock]

I know there was a good bit of corrosion on the nose (all) of this gearcase. But I don't remember there being this big a divot. It seems to be bigger and now there is a shiny spot. Maybe I hit something? I did go out a few days before by myself. I went a little faster that day (1 MPH) and nothing happened. Boat drove great.


Attachment 537052

Might very well be you hit something submerged and it was really not a blow out but just an unfortunate contact with something.

Rock

[whipper]

One bump to many with that skeg and really the case shape needs some work. When ever ya wana go fast the gearcase gets more important the faster ya wanna go. Setup is key. Hull wasnt set still rocking a little also. Ballance for passenger ect.. No offence just want everyone to boat safe. Anytime your on the pad its the little things that count. You very well could have created a big bubble that worked its way back to the prop with the skeg and nose shape ya got going on there. plus the leading edges could use a major file job. i would spend a day cleaning that bad boy up a little. Grinder,emery cloth and looking at fast cases will help you get a shape. i would cut the skeg with a zip cut first and foremost like the lines i drew. Something like that to get rid of the big non hydrodynamic chips. lol You could also file one side of the trailing edge of the skeg to counter prop rotation. Polish the Nose cone and whole case so it shines. There are lots of little shape things to make that case a lot better with a file and plan.There are lots of design tricks for lower units. Good luck

[whipper]

That top leading edge make smooth not sharp but not all nicked up like it is. easy. Were that chunks out sand grind carefully to shape it as nice as possible so that the chunk is more less prone to scooping water and it flows better. Thats what I would before I tried going that fast again. Also triple check after were your prop shaft at even with the pad is and mark your gage were that is and stay just below it. Cheers

[whipper]

Or time for a good case. haha You can make that one a little better. but its still crap. haha no offence.:]

[Aaronhl]

Could the shape of the skeg cause blow out, by shape I mean how some skegs are flat at the bottom and some curved, thick about how the skeg wears like you are hitting the sandbar shallow water if that makes sense

[CUDA]

Check everything for tightness, I never heard of blow out at 70 MPH

[skialot2]

That case was highly corroded. It had lost a nose cone. It had a giant crater in the front of it. The skeg was worn 3/4 off. Running at the pad with a transom mounted pickup. Not shocked it blew out. But the gears worked good and it didn't leak. So I cut that case open and took all the internals out. Everything was in perfect condition. I put it all in a like new CLE case I had. Bought all the tools and did it myself. On my FrankenMerc and ready to go.

[whipper]

That case was highly corroded. It had lost a nose cone. It had a giant crater in the front of it. The skeg was worn 3/4 off. Running at the pad with a transom mounted pickup. Not shocked it blew out. But the gears worked good and it didn't leak. So I cut that case open and took all the internals out. Everything was in perfect condition. I put it all in a like new CLE case I had. Bought all the tools and did it myself. On my FrankenMerc and ready to go.

Thats better !!! And yes the shape of your skeg could cause the blow out. Combo that with the dent in the nose giving you bubbles from the start it was a bad combo. haha I have the same CLE on my Allison with an Allison cut skeg and massaging hear and there.

[r.c.]

Good thing you boys came out from it ok . I'm with donmac on all he said on this one, it spun out bc the motor was to high and crabbing.Not a blowout. Yea the lower needed work to say the least.

[skialot2]

Good thing you boys came out from it ok . I'm with donmac on all he said on this one, it spun out bc the motor was to high and crabbing.Not a blowout. Yea the lower needed work to say the least.

Well I have been running at the same height since then with a different case and no problems. It wasn't crabwalk. I have experienced that a couple times before. This was different. Instantaneous loss of control. You can hear a weird sound and a quick spike in rpm before I lift off the hotfoot. What ever it was, it wasn't fun.

[Aaronhl]

Not sure if this was said already, but I was wondering if the 3 ram trim is any good past 70 when surfacing the prop, cuz if you let off the gas slightly will the trim think you hit something and pop backwards?? It holds while you are giving it gas but then will the water pressure on the lower unit cause it to trim up when not on the gas ??

[Onetime]

I’ve heard of that but never experienced it. I run ratcheting cases so maybe that’s why I’ve not experienced it.
I can see were a non ratcheting could do that.

[LakeFever]

I’ve never had any issues with the 3 ram either but I too am running a ratcheting case but it almost never ratchets. I’ve only heard it a couple of times. The three ram trim is too slow for me now. At high speeds it feels like forever for the trim to respond. I’m hoping to swap to a single ram smooth back osm sooner than later

[skialot2]

A correctly working 3 ram trim will not pop up when you lift off the throttle. It will if you hit something. There is valving to stop it from happening otherwise it would happen every time you put it in reverse and give it gas.


Merry Christmas

[RiverRat71]

My 2.5 XS was 3 ram. Got out of the gas hard a few times at 80-90 with prop shaft 1/2" below to even with pad & no issues. Non ratcheting torquemaster. RR