Cavity Plate

[Hightower]

Originally Posted by jyasaki

You'd need to remove the leg and disassemble completely to weld it up. And be damn careful that things don't warp.

Had a friend who broke the skeg off a new Suzuki motor; he had a muffler guy weld it back on a grind it smooth. Next trip out the gearbox disintegrated due to water ingress through melted seals. Luckily for him, Suzuki decided to cover it under warranty, despite the "remove shoe, shoot foot" procedure that got him there.

Personally, if I was going to effect a repair, I'd use a steel putty type epoxy, and fair it out a bit along the remaining plate. It's not going to hold against a lot of load or anything; it's just there to isolate the prop from the surface.


jky

You could just dunk the whole lot in a bucket of water whist welding it, but I suspect that with the amount of metal around the area that the heat would dissipate before warping of the gear case would take place.

[Tim M]

I've seen this before. It was caused by a line which was tied onto one of the transom eyes which fell over the back at speed. It got wrapped around the prop which pulled it tight, the force of which was enough to remove a similarly sized chunk out of the cav plate. No other damage was done to the engine (although the rope probably came off pretty bad!).

PS. I see in the first pic there is some paint missing on the prop. On the prop from the above situation you could see marks around the base where the rope and rubbed some of the paint off.

[9D280]

If it's any help, When I was looking at the various ways I could get PT onto mine, I discovered that the leg off the 75 is shared with quite a bit (incl Yam & Mariner) from about 50 - 90 HP.

Any breakers near you? Might be cheaper & easier to get a replacement gear case - your seller may be more willing to give you back a few hundred quid for a spare part & the hassle than the whole lot. I didn't cross check gearbox carryover, but from memory there are essentially two types - the old ones that take a smaller dia prop & the newer "K-series" size.

There's someone I saw recently on Ebay breaking a Merc 75 - NS marine?


I do wonder - the port list problem down to your hydrofoils not being particularly horizontal?

[PeterM]

Originally Posted by 9D280

I do wonder - the port list problem down to your hydrofoils not being particularly horizontal?

It all suddently seems obvious when I read this ! Likewise the fitting if a 'used' caseing for a few hundred quid to fix the problem.

I wish I could think of these things !

[Bigmuz7]

Neil. .. if you can get the lower leg off .. drop it into West of Scotland Engineering, at Yorkhill in Glasgow , they will repair it to a standard you wouldnt have known there to be any damage. I used to catch/snap bits off my skeg on my 135, 150's and they straightened and welded them to perfection, and if there is any doubt (David Somerville , the owner) will tell you he cant do it but this would be unlikely IMO. Perhaps you could recoup some cost from the vendor, but if not, its one of those 'down to experience' ones, but I'm sorry you've had that experience from some scumbag .. He'll fill in the holes on the other side too, but before doing anything, test the boat to see if your problem is cured, to be sure you dont need to put the fins back on

[neil.mccrirrick]

That's good to know, thanks. I live in Oldham so its a bit of a haul to Glasgow, but may well be worth the trip for a good job. I'm hoping to get out on Sunday and see how it goes with hole, then take it from there.

Thanks for all the help guys, you have somewhat lessened the shock I felt when I pulled the foils off and felt my chin hit the floor.

While I was up in Oban picking the engine up, I blew the catalitic converter on the car, which to cut a long story short meant I had to leave earlier than I expected. But for that the foils would have come off up there and this would have been sorted there and then.

Still life's never dull eh :-)

[Bigmuz7]

Ah! sorry I saw Oban in one of your posts and looked no further ..sorry .. doh !

[IBWET]

We seem to have moved on from the cause of this a little, but I have seen this before. It was due to some dopy sod trying to changed the impeller,without the knowledge of where all the bolts are.... I, I mean he, had never done it before and didn't know about the bolt hidden under the anti torque anode at the back of the leg. so I, I mean he, preceeded to hit it with wood,resulting a perfect replica of your damage what a donkey I , I mean he felt.

However it's not the end of the world, It was repaired using chemical metal sanded (cost next to nothing) and painted you would never have know it had happened. lasted 7 years like that. On your new boat, check the shafts not bent If it was an ally prop unlikely, new prop and your laughing..

[Downhilldai]

Does Wavelength know you, sorry, I mean your friend?

http://rib.net/forum/showpost.php?p=289380&postcount=8

[neil.mccrirrick]

Originally Posted by IBWET

We seem to have moved on from the cause of this a little, but I have seen this before. It was due to some dopy sod trying to changed the impeller,without the knowledge of where all the bolts are.... I, I mean he, had never done it before and didn't know about the bolt hidden under the anti torque anode at the back of the leg. so I, I mean he, preceeded to hit it with wood,resulting a perfect replica of your damage what a donkey I , I mean he felt.

However it's not the end of the world, It was repaired using chemical metal sanded (cost next to nothing) and painted you would never have know it had happened. lasted 7 years like that. On your new boat, check the shafts not bent If it was an ally prop unlikely, new prop and your laughing..

Chemical metal? Is that the same as this:

--------------------------------------------------------------------------------

http://cgi.ebay.co.uk/QUICKSTEEL-Qui...3A2|240%3A1318

That Rogue Wave has made me aware of?

[Downhilldai]

A decent looking lower unit for you in this box of goodies. You may even be able to swap the relevant parts over to convert yours to a 90.

http://cgi.ebay.co.uk/mercury-70hp-9...1%7C240%3A1308

[jyasaki]

Originally Posted by Hightower

You could just dunk the whole lot in a bucket of water whist welding it, but I suspect that with the amount of metal around the area that the heat would dissipate before warping of the gear case would take place.

I'm not sure that would protect rubber seals. They're a bit more temp sensitive than aluminum.

jky

[Rogue Wave]

yep that's the same stuff. I guarantee you it will repair your anti-ventilation plate a treat and with minimum fuss. If you get cracking you could have the hole jon done in 4 huurs including 10 minutes of standing back and saying wow what a good job I just done. Fill the holes for the doel fins so you are not tempted to put them back on.

[codprawn]

Yes it's good stuff - have used if for loads of things - from fixing the bog to filling break through cavities on a skimmed cylinder head.

[neil.mccrirrick]

Thanks all for the advice re this. I fitted a tilt pin, which has stopped me trimming too low, and that seems to have cured the tilt issue, obviously the hydrofoils are off so that may have done it anyway.

Filled the hole with quicksteel, at which point it looked like this:

[neil.mccrirrick]

Some paint, and now it looks like this

[neil.mccrirrick]

O and I've changed the prop and painted the skeg as well.

So all in all very happy, lets see if I can knock the lot out on the way to the IOM

Hopefully all this will be useful in the event some other poor soul has the same problem. Got to say that stuff is excellent.

[jambo]

Great job neil glad you are back in the water

J

[al40]

Yes good job... I did the same as IBWET, sorry his friend, and also did the chemical metal repair. That was 5 or 6 years ago and it still looks fine.

[Hightower]

Yep, good to go! Nice job.