RIB transom stress fractures - cause for concern?

ddd333 · 09 May 2013, 02:39

I noticed the other day I have some hair line stress fractures on
either side of the outboard. My AB rib is only rated for 75hp but
currently has 90hp. Should I be concerned at this stage? Or is this
quite common and just something I should keep an eye on but not
worry about much? Do you guys suggest I gel coat over the cracks
to prevent water getting inside?

Any suggestions or advice is appreciated.

henryfreston · 09 May 2013, 06:36

I would be concerned. Considering you are 15hp over the max allowance and it is a 4 stroke. The transom is obviously under too much strain.

Poly · 09 May 2013, 07:24

much has been discussed on transom cracks in the past. Those look like proper cracks rather than suface crazing (there is some of that too). In which case they need repairing properly: grind our old gel, make sure material underneath is sound and dry. Consider reinforcing. Repair gel.

Unless you do something to beef it up / reduce load then it will happen again with the new gel.

Dirk Diggler · 09 May 2013, 07:30

Quote:

Originally Posted by henryfreston

I would be concerned. Considering you are 15hp over the max allowance and it is a 4 stroke. The transom is obviously under too much strain.

lol, so it's a bit like a sell by date on a packet of sausages, eat by the 27th coz on the 28th they'll poison you!

the transom requirements for a 75, 90 or even a 200 hp motor are the same, if it's showing signs of letting go, it's because it wasn't built that well, not because it has a slightly bigger motor than it's rated for.

matt h · 09 May 2013, 07:38

I wouldnt be happy with that , as the boys say, get it looked at cos it aint right! Send me ya engine and will give you £2000 for it !!

thomas · 09 May 2013, 07:41

If you are worried then find a friendly surveyor with a thermal imaging camera - that will show up and serious concerns, on here you'll just get opinions as no one can really see whats under the gel.

willk · 09 May 2013, 08:26

Quote:

Originally Posted by Dirk Diggler

lol, so it's a bit like a sell by date on a packet of sausages, eat by the 27th coz on the 28th they'll poison you!

I'd REALLY enjoy listening to you explain to Mrs willk why that isn't true...

Dirk Diggler · 09 May 2013, 13:24

Quote:

Originally Posted by willk

I'd REALLY enjoy listening to you explain to Mrs willk why that isn't true...

yeh, tell me about it. My wife can be a couple of hours doing the supermarket shopping, just coz she like to check sell by dates, and of course contents.

simon23 · 09 May 2013, 18:37

Is the transom designed to carry the weight of a outboard or the thrust of a outboard.if its the later you should only run at 5/6 revs and it should be fine

Sent from my GT-S5830 using Rib.net

Erin · 09 May 2013, 20:38

Quote:

Originally Posted by thomas

a thermal imaging camera - that will show up and serious concerns,

Explain please. How does cracking give a thermal signature?

thomas · 09 May 2013, 21:04

When I bought my last yacht I use a surveyor who scanned the hull with his thermal imaging camera, you could see everything, cracks, weaknesses and the makeup of the hull - have a look in the gallery section of International Yacht Surveys Hamble Southampton - Marine Yacht Inspections Surveys. and you'll see what I mean.

Rogue Wave · 09 May 2013, 21:09

Quote:

Originally Posted by Dirk Diggler

yeh, tell me about it. My wife can be a couple of hours doing the supermarket shopping, just coz she like to check sell by dates, and of course contents.

probably gives you enough time to clear out the hot food section

hopr your'e well sir

ddd333 · 09 May 2013, 21:18

Thanks for all the replies.

I think I will get some custom aluminum "L" shaped plates made up, bolt those on after some gel coat work and see how if goes.

Cheers!

Jorgos · 09 May 2013, 21:44

Quote:

Originally Posted by ddd333

I noticed the other day I have some hair line stress fractures on
either side of the outboard. My AB rib is only rated for 75hp but
currently has 90hp. Should I be concerned at this stage? Or is this
quite common and just something I should keep an eye on but not
worry about much? Do you guys suggest I gel coat over the cracks
to prevent water getting inside?

Any suggestions or advice is appreciated.

I will say something different.
Sure is not the best thing.
But tis is only the top cell of your boat.
Motor normally is relying on the stern , so if you can have a good look what is happening undernith , could be that this stress is not that realy important. .

I would not worry so much if there are not any more signs of damage internally.

Usually 75 and 90 hp motors have the same weight and they are many excamples internationally tha they dont give trouble and boats are calculated for much more weight!!

mister p · 09 May 2013, 21:48

Do you tow it with the engine down?

kerny · 09 May 2013, 22:54

Quote:

Originally Posted by mister p

Do you tow it with the engine down?

Naughty ,Naughty mister p

ddd333 · 10 May 2013, 02:02

Quote:

Originally Posted by mister p

Do you tow it with the engine down?

No, I just have it like that so it fits in the parking stall.

ddd333 · 10 May 2013, 02:05

Quote:

Originally Posted by Jorgos

I will say something different.
Sure is not the best thing.
But tis is only the top cell of your boat.
Motor normally is relying on the stern , so if you can have a good look what is happening undernith , could be that this stress is not that realy important. .

I would not worry so much if there are not any more signs of damage internally.

Usually 75 and 90 hp motors have the same weight and they are many excamples internationally tha they dont give trouble and boats are calculated for much more weight!!

Thanks for your opinion, I'm tempted to gel coat over it for now and see
if it gets any worse. Its a 90HP 2 stroke which is probably about the same
weight as the 75HP 4 stroke.

boristhebold · 10 May 2013, 07:29

I think you have more to worry about than the cracks, if your boat is rated for 75HP and you have 90HP and presumably you have insurance, what do you think the insurance company are going to say if you have any claims, consider worse scenario as in an injury or worse to a passenger or others, you might find you are personally paying out for the rest of your life.

As to the crack, you really need to remove the gel coat and have a look under it, it may just be gel coat cracking but it could be worse under it.

mister p · 10 May 2013, 08:26

Well, if you don't tow it with the engine down that removes that as a possibility of stressing the transom incorrectly.