Advice: Structural Problems?

DJL · 24 June 2003, 14:00

My RIB has developed a crack where the transom intersects the deck. The crack runs along almost the entire width of the transom. Furthermore, when pressure builds in the hull cavity due to temperature change, air is forced out through the crack; seen as bubbles when there is water in the boat. Conversely I’m sure water is seeping into the hull cavity through the crack.

The RIB is now 1 month out of warranty but I have sent a letter to the manufactures explaining the problem.

The question is how serious a problem is this likely to be?

All comments, opinions greatly appreciated.

Daniel

DJL · 24 June 2003, 14:02

Slightly useless picture of the crack.

Julian · 24 June 2003, 14:41

Daniel

Your probably just find that its a Gel coat crack and nothing serious at all. All Ribs show stress marks eventually and most can be easily filled and polished out. Check with the manufacturer as well though.

Julian

Alan · 24 June 2003, 14:51

Obvious answer (so I may well be wrong then) is that the transom is coming away from the deck. Considering the forces upon a transom this is not unheard of in RIBS. However in a relatively new boat it is a cause for concern. You are correct that water will be seeping into the crack which in the fullness of time will rot away any wood in the deck construction. (e.g. if you deck is marine ply covered with gel as per a large number of RIBs.)

I had a similar problem in my Deep Sea 21 a few years ago. In this case the crack and flexing was from the "knees" that led back to the transom and was resolved by fabricating dirty great stainless brackets and bolting through the knees and transom. Not familiar with your type of RIB but cant see any knees on the pic so mebbe a different construction. You might get away with putting some hefty stainless L brackets between deck and transom and filling the crack. But not on a newish boat surely?

You need a) to tackle the manufacturer / dealer. (Who will probably point out something helpful along the lines of "well if you will go an use it in the sea what do you expect!") and b) assuming you get no joy get some expert opinion on cause and rectification. Suggest you then create merry hell with dealer/mfr, threaten sale of goods act, small claims etc etc.

Good luck!
Alan

John Kennett · 24 June 2003, 15:19

From your description of the bubbles it seems unlikely to be just the gel coat cracking, and may well be more serious.

I hope that the manufacturer doesn't try to duck any responsibility because the boat is over a year old. This sort of thing shouldn't happen in a boat of any age.

Do keep us posted.

Cheers
John

Manos · 24 June 2003, 15:27

Quote:

Originally posted by DJL
The question is how serious a problem is this likely to be?

Without close examination by an expert all is speculation.
Most likely as others suggested is a gel coat crack but also you mentioned bubbles so it may be more serious than that.
However, the question is how long has been there?? If it has been for a long time you might find (this is the worst case) that the ply under the jell coat is rotten or damaged and may need repairing.
Is all very easy to be repaired by an expert ONLY!!
But you should take it up with the manufacturers before you do anything else.

DJL · 24 June 2003, 17:07

Thanks guys,

I personally think it’s more serious than cracking gel coat. If it is more serious I’m not sure what they would do about it. I don’t cherish the though of the deck/transom being cut up and repaired which is really the only option apart from a new hull. I bought a new boat to stay away from these kinds of problems and their repairs.

Hopefully I should get a reply from the manufacturer in the next few days.

Cheers
Daniel

Pete7 · 24 June 2003, 17:19

Daniel, ignore Manos he is talking twaddle again. The deck is unlikely to be rotted on a one year old boat. GRP is very suitable for use by amateurs, for repairs. The bubbles are from air escaping. Lots of ribs do this from the fastenings particularly when you put a boat hot from the sun into cold water.

Agree with JK though ask the manufacture to have a look at your boat. If you want a pic of Stainless Steel transom supports just shout and I will post one of my Ribtec that had them fitted from new.

By the way what make is your rib ?

Pete

thorper · 24 June 2003, 17:51

Daniel - sorry to hear about your problem. Can you let us know what Laurence Lock at barnet comes back with? When we had a problem with our tornado he was helpful, although that was when the boat was new. Hopefully they wont have to send it all the way back to Hull for fixing.

Ricky

crazyhorse · 24 June 2003, 17:54

Its great on here post a picture and everybody knows what the answers are ? withought the need for a thorough inspection.

Anybody now the lottery numbers for next wk?

John Kennett · 24 June 2003, 18:36

Nobody has claimed to know the answers. Several people have made useful suggestions about what the cause might be and possible courses of action.

Do you have anything useful to add?

John

Powerboat · 24 June 2003, 18:42

Hi Daniel,

A few thoughts....

Firstly, all Ribs will develop stress cracks along the transom area indicated in your picture - and within days of first being used.

Think about the transom . It is basically a large lump of wood being pushed by an engine that just happens to have a boat attached to the front. The transom is trying to push itself into the boat. For this reason most transoms have triangular bracing supports port and stbd from the floor of the boat to the transom to take the forward stress. From the pics , yours do not.

Cracks will allow water to seep into the wood under the grp. If the wood is marine ply , no great probs ..If it is ordinary ply then the transom will absorb water swell and delaminate. This ( believe it or not) was a common fault recently with a manufacturer better known for their engines than their mass produced RIBs!

According to your profile, You have a small boat (4.7m). Normally such a boat would be fitted with a 40 hp 2 stroke for general purpose or at most a 50 hp for performance use. You have a 60 hp and a heavier 4 stroke at that !

This would seem to me to be way over powered for the boat you have. Given the fact that there is no transom bracing, I m not surprised that that you are experiencing cracks ... Big heavy engine , small RIB and no transom bracing.

Don't know who the manufacturers are and if they or you fitted the engine and if the engine is within their own guidelines for max HP.

If the manufacturer fitted the engine, I would expect them to honour the warranty even if it is a month or so out. If they do tell us all about how good they are..

If they don't....Name and shame !

If you fitted the engine and if it exceeds max reccomended HP, then I am afraid that you may be to blame.

I am not in favour of add on bracing brackets. Certainly I always advise any of our clients to run a mile from a second hand boat fitted with them as they smack of a cut and shut car !

The transom is the single most important component of your boat. Get it checked professionally !!!!!

Hope this is of help !

Stuart

crazyhorse · 24 June 2003, 18:46

Yep Jk it looks like its cracked to me?,

It needs inspecting buy the builders and seeing what deal you can get under the fit for its purpose laws.

Cookee · 24 June 2003, 19:13

My opinion for what it's worth - ignore Manos - listen to Powerboat, although if you can imagine the engine is actually trying to pull the top of the transom backwards.

The reason that raceboats suffer so much damage in this area is jumping them - every time the boat lands and the throttle is opened, there is a lot of horsepower trying to rip the top of the transom away from the boat.

Having said that if manufacturers can keep 200 or even 400 or 600 horsepower outboards on the back of a boat it shouldn't be hard to cope with 60 hp, it's just a question of construction.

As per the others it's almost impossible (in my view) to diagnose this at a distance, and even lookig at it in real life may not tell you that much unless you are familiar with the way the boat was manufactured.

Wish I could help more.

kitten · 24 June 2003, 22:08

Quote:

Originally posted by Powerboat
Hi Daniel,

A few thoughts....

Firstly, all Ribs will develop stress cracks along the transom area indicated in your picture - and within days of first being used.

Why do people think like that, it lets manufactures get away with all sorts of sh*t.
Not all ribs crack, and if they do then they arn't built right.

Gell cracks are very different from structural faliures, and if the structure is sound then how does the air get through it?
Given the relative strengths of wood and grp, even a basic csm lay up, then if the glass is broken so is the wood.

Daniel, if anyone looks at your boat unfortunatly they will not know what the extent of the problem is without destructive investigation. Don't trust any one who says they can, best they can hope for is to make an educated guess, though if you get the right person then that guess can be fairly accurate.
If this is not a common problem with that model, which I susspect it is, then the build is wrong, give the builders hell.

gavin · 24 June 2003, 22:19

Is your rib an Avon, maybe not I have seen triangular bracing glassed into the floor / transom on some of their models to help relieve the stress, have you any word from the manufacturers

Powerboat · 24 June 2003, 22:58

Kitten,

I didn't say all RIBs crack.....I said that all RIBs will develop stress cracks along the transom ...meaning that in my experience that with flexing after first being used small stress cracks or crazing will appear in the gel coat . These can quite easily be touched up .

A slight exageration I think to say that all RIBs crack !

Of course bananas peel and go mushy after time I believe !!!

Best wishes,

Stuart

jwalker · 24 June 2003, 23:05

Yeh I agree with much of what Kitten said. Give the builders a hard time. Despite what others have said here, the problem is obvious - the eff'n thing is cracked and it shouldn't be. I bet there is no join of the marine ply to the transom exept the surface layer of csm. It needs grinding out and grinding a long way up the transom and along the deck because new resin does not adhere to old cured resin as well as you might like. Personally, I'd apply a couple of layers of csm, while it is still wet screw a chunky batten to the floor and to the transom and then over coat it with 2 layers of csm, one of diolen, 1 of csm, one of diolen and finally a coulple more of csm. stagger the edges of the layup so as to feather it into the hull/transom. A good way of raking up the old fibreglass is to hammer masonary nails into a mallet and grind off their ends. Use this to chip up the glass fibres to give a nice hairy key.
It could do with a couple of knees in there too.

This, of course, if you don't get any joy from the manufacturer.

JW.

Powerboat · 24 June 2003, 23:16

If it was / is a structural rather than a cosmetic problem , I'd be looking for a new boat or my money back to buy a different boat rather than throwing good money after bad repairing a cock up.

Nice tips though JW on the repair techniques!!!

Why no knees I wonder ?

Seems like very little structure to handle a 60 4 stroke..

Best wishes,

Stuart

jwalker · 24 June 2003, 23:21

Ta.

JW.