Skeg question

[FCnLa]

My boat used to run totally unruly. I spent many hours on my back straightening out the pad until I had a 72" straight edge flat with no gaps. It ran much better, but still some problems. Boat is a tunnel (two sponson with a center pod) a 235 Rude with a L&S nose cone and torque tab. It kind acts like it is chining, and no, you cannot drive through it! :eek:

The question is: Would a slight curve in the skeg cause the boat to run funky? It is bent up at by the gearcase itself. I noticed it when I was replacing my nose cone after hitting a log at around 90. I beat on it and epoxied it so that it is some what better.

Another question. There is a guy close that will replace the skeg. Has a uses a mill to machine it off and a jig to put the new one on.
Will a welded on skeg be safe? Put on a welded on torque tab too? Really do not what to spend a lot of doe on a new housing.

Thanks!

[Talon2.5]

i ran a welded skeg in the low 90's and had no problem but many have said not to do it, but that safety issue is something you have to decide whether ya want to risk it, the ball is in your court on that one


later skip

[Tony Brucato]

That kind of repair would be OK on a 40 MPH fishing boat, but at the speeds your rig is going skeg failure can be deadly.

The aluminum in your gearcase housing is an alloy that is more brittle and porous than billet aluminum and is not designed to bend. If you don't believe it, put an old skeg in a vice and bend it back at forth a few times. The metal fatigues easily and will fail.

In particular the location of your initial damage is at the top near the bullet. This area is the most critical and because of leverage receives the most stress. Failure at this location on an aired out tunnel hull would allow the prop to paddlewheel the back of your boat sideways! Results could be catastrophic.

Damage that is confined to the lower inch or two could be safely repaired by a competent shop familiar with high performance boats. They wouldn't cut it straight across for the repair, but instead make a zigzag splice on the housing and replacement. This reduces the amount of stress concentrated on the weld.

I know it's a lot of money for a new housing, but it needs to be done. Please be safe.

[Flat Out]

I'm with Tony on this one. A repaired skeg on a Hi-perf boat is not the way to go. A new or good used case, add a Bob's or other hi quality nose cone is the best way to go.This not the cheapest but the best never is. Safe Boating:D

[us1]

What ever you do, DO NOT weld a skeg on, it will come off at the worst possible time. Many racers have been killed by skegs coming off.

[AnthonySS]

GOOD Advice Guys!


....seeing more and more skeg failures everyday! Especially on 100 mph rigs!

So far the best solution has been an "Unmodified" SM

[BarryStrawn]

I would also not weld a skeg on a high performance rig. Not worth the risk.

But you may be able to straighten an OMC. At least I have always made my own torque tabs by metal shaping the OMC skeg with a hammer, dolly, and file. I am told this is not possible on a Mercury. You just make chunks of Merky metal. Different alloys and heat treat. I have also straightened one OMC that was bent maybe a half inch in a rear end trailer accident. All my stuff is mid 80's and older so they might be different now. Original case on your 235 should be the same.

Can you post a picture? Do you think this happened when you hit the log? This may show how the alloy is malleable rather than brittle. If yours is just curved in the tail starting up at the case then I would bet you could straighten it. But it sounds like you already tried. If it is bent up in the thick section, then I don't know. Another thing to consider is the case bore might also be distorted by the impact. For certain, remove all the paint and epoxy for a good crack check at the machine shop. But it probably is time to look for a replacement.


Barry

[Matt]

I had a welded skeg come off at a little over 7000 rpms. Not very fun at all and not worth the risk. Luckily I kept it topside up. Sport Masters and Torque Masters are losing skegs for no apparent reason right and left from the factory so don't chance welding one on. Do you have insurance? Hitting a log should be a claim they couldn't argue with you about. Doesn't have anything to do with the speed of your boat.

Matt

[FCnLa]

No, not insured. I don't know if it happened when I hit the log or not. I have seen aluminum welded with great success (on aircraft parts) and thought it would hold up. Thanks for your advice, and points well taken. It has no cracks at all. I will be looking for another housing and/or slap some more epoxy on it and try that. Just most of the housings you find used already have a bent skeg. It is only bent on the leading edge. I don't want to take any chances. I have heard of skegs failing before. Not a pretty sight. I only wish I would have seen it before installing a new nose cone!

Thanks Guys!:D

[Jimboat]

I agree with those that recommend NOT to weld your skeg. Aluminum is very difficult to weld properly. It is a material that will "work harden", increasing it's already brittle nature, and reducting it's ultimate strength. Bending or "banging" aluminum or "working" it in any way will definately reduce it's strength and shorten it's life. Bottom line is - for a hull going as fast as your's, it's not worth even thinking about "fixing" it. Get it replaced by an expert. Suggest Bob's Machine. They really know what they're doing with lower units.

[BarryStrawn]

Jim,

Just because a metal is worked does not mean it is weaker. Many alloys of aluminum are "tempered" by cold working. This increases the strength. The problems arise when the wrong alloy is worked to excess. I will grant you that randomly banging on a piece of "aluminum" is a bad idea. A very bad idea on the Mercury "X" alloy from what I have been told. But you can shape the skeg on the old OMCs which is what FCnLa was asking about. Some skill required. Might be stronger or might be weaker from the working. I dunno but mine don't fall off and have seen 100mph plenty of times.

On a related issue, are you familiar with Darris Allison's skeg patent #6,155,894 of December 5, 2000. Covers a lot of ground with replaceable and off-center mountings. Made me think about some possibilities and want to experiment. But I don't have any gearcases with bad skegs. I can email a PDF if you want it.


Barry

[Jimboat]

I agree that the cold working won't, in itself, weaken the material, but with aluminum, will usually increase hardness and reduce ductility, often leading to cracking. I find it's very difficult - unless you really know what you're doing with aluminum - to know whether you are annealing at the proper recrystalization temperature. I've found aluminum to be very "finicky" that way. It doesn't usually come out with comparable ductility. So I take the chicken way out!

I don't feel comfortable with running at 100mph with a coldworked skeg, or worse, a rewelded one. Maybe I'm over cautious. I've seen some pretty severe brittle fractures, and don't want to be going 100mph when one happens.

I'd be interested in your article on the Darris Allison's skeg patent #6,155,894 of December 5, 2000. I'm not familiar with it, but sounds interesting, particularly the off-center mountings.