Transom-Deck Joint crack Pictures - Zodiac Medline 3

shahid · 14 August 2009, 21:10

I'm enclosing pictures taken of a Zodiac Medline 3 RIB with what appears to be a crack on the Transom-Deck Joint.

Haven't noticed any water in the bilges yet, though the appearance of said crack is worrying me.

As you can see in the overall views, there's caulking on both extremes, while the center section appears to have opened out. Normally one would have expected this area to have been glassed over but zodiac seem to have used caulking.

What would be the best course of action to repair this. I really want to avoid dismounting the engines for repairs but looks like that's what I will have to do.

I would very much appreciate any advise on the same.

Cheers!
Shahid

Bigmuz7 · 14 August 2009, 21:14

get the motors off and take the pain

... welcome to having a lot of power and weight on the transom .. rebuild ahead I'm afraid ! Still ,.. it is not impossible to sort

chewy · 14 August 2009, 21:21

Its not a crack as such is it? Just looks like the two mouldings have parted company?
Still needs looking at either way.

Bigmuz7 · 14 August 2009, 21:29

well I wouldnt take my nearest and dearest to sea in it,.. round the parts I go

shahid · 14 August 2009, 21:52

Chewy, yes it's not really a crack...more of a parting. The course of action that I'm considering as of now (pending more inputs from you experienced ribbers) is dismounting the engines, removing old caulking and cleaning the surfaces, injecting new sealant and glassing over/ applying gelcoat.

Do you think inserting a couple of thru bolts would be a good idea?

The season here will only start in october after which she will be in a swinging mooring.

Bigmuz, when you say "rebuild" do you mean a transom rebuild or what I mentioned above? The person I bought the boat from had opted for the twin engine setup, I would have probably gone for a single.

chewy · 14 August 2009, 22:07

Sounds like a good plan mate, the engines will need to come off, the old sealent removed and surfaces cleaned.
Use some form of Sikaflex (221 or 291) to seal it then like you said a few bolts through won't go a miss.
I wouldn't glass over it or gelcoat it just leave it as it is.

shahid · 14 August 2009, 22:18

Thanks! Feels good to have some reassurance, will post an update once I get the work done.

chewy · 14 August 2009, 22:23

Is the moulding just the splash well joined to the hull?

Bigmuz7 · 14 August 2009, 22:26

the trouble is .. you dont know how far down it goes

The thing with ribs is that they only usually have two 'knees' that take the engine loading on the transom to the deck and the hull. i.e unlike most power boats which have 'sides' as well, so its an inherently weak design, and if they fail .. your outboards are connected to fresh air .. so any damage on the transom is inherently a failure throughout the whole stern as far as I'm concerned.

Every case is different, but your case looks like a common problem and one I have experienced myself

Youve got to remember .. next time you come flying off a wave.. and land in the next one .. your engines will develop an immense thrust on your transom and hull, and every jump you do will weaken it further .. YOuve got a break the whole way across the top which is total structural failure IMO

You need professional advice to get this sorted IMO

chewy · 14 August 2009, 22:29

JUst read your post Muzz.
From what your saying it could just be the engines holding the two mouldings together worse case scenario?
Bad design if it is?

Bigmuz7 · 14 August 2009, 22:45

Quote:

Originally Posted by chewy

JUst read your post Muzz.
From what your saying it could just be the engines holding the two mouldings together worse case scenario?
Bad design if it is?

KInd of .. but its worse than that.. the transom is bonded to only a few bits of wood below the deck

The leverage provided by an outboard on the transom is absolutely massive.. and its about 6 inches to a foot above the join on the deck on most ribs, so it doesn't surprise me that they break. My current boat has a box arrangement in front of this joint and is inherently stronger

shahid · 15 August 2009, 07:29

Quote:

Originally Posted by chewy

Is the moulding just the splash well joined to the hull?

That might be the case, is there an easy way to find out? I've also emailed Zodiac and am waiting for their "excuse"

If that is indeed the case, what are the implications? I'm enclosing a few pictures of the transom taken during the prepurchase survey in France (surveyor didn't bring out the subject opening).

As you can see from the topside picture of the splashwell, The engine mounting bolts are seen evenly spaced out from the inside of the transom just below the steering system.

JSP · 15 August 2009, 08:37

Is it something wrong with the transom though? Or just where the splash well sits on top of the transom? That would explain why it's just had a sealant in between the two? If it is just that (and I'm not the most experienced on here by a long way) will it be structural?

Bigmuz7 · 15 August 2009, 08:38

That surprises me to see separation from that design .. you have the supports at either side but not in the middle, but you also have the floor that should make that set up quite strong IMO. Looking at the pics again looks as if it has been filled by someone before, and it has just opened up again, after some use.

Was the presale survey carried out by the vendor or arranged by the vendor ? Do you know the person who sold it to you ?

shahid · 15 August 2009, 08:47

Quote:

Originally Posted by JSP

Is it something wrong with the transom though? Or just where the splash well sits on top of the transom? That would explain why it's just had a sealant in between the two? If it is just that (and I'm not the most experienced on here by a long way) will it be structural?

I can't figure that out yet. So far the only indication is the visual separation as seen in the pictures. There's no signs of leakage or water entry into the bilge.

shahid · 15 August 2009, 08:53

Quote:

Originally Posted by Bigmuz7

That surprises me to see separation from that design .. you have the supports at either side but not in the middle, but you also have the floor that should make that set up quite strong IMO. Looking at the pics again looks as if it has been filled by someone before, and it has just opened up again, after some use.

Was the presale survey carried out by the vendor or arranged by the vendor ? Do you know the person who sold it to you ?

The boat is 2001 built and apart from this seems to be very well looked after. No rattles anywhere.

I'm a surveyor myself (although dealing in mobile offshore units, oil rigs and the like - not so much experience with FRP and small craft) and I arranged the survey through an associate in Europe (who will be hearing from me!!)

Leo · 15 August 2009, 09:05

I agree with Bibmuz for the first reason that this happens. But there’s a second reason: you have to keep in mind that there’s a lot of weight hanging on to the transom while trailering (hope you write it like this) What I mean is that when you’re on the road approx. 400KG will bounce on every hole in the road and gives a torsion on the transom. You can prevent this by make standaards for the tail of the motors to the trailer and keep the weight of from the transom. The repair won’t be difficult in this case I believe, I agree with repairs as mentioned.

shahid · 15 August 2009, 13:00

Here's a picture of another medline 3 transom I found on the net, this is probably how it was supposed to be originally.

I'm reposting the picture of my boat's transom next to it for comparison

Bigmuz7 · 15 August 2009, 14:19

So they dont lap the top of the transom over, and just fill the gap between the top/deck and hull ?

or is this another 'failed' one ?

shahid · 15 August 2009, 14:23

Quote:

Originally Posted by Bigmuz7

So they dont lap the top of the transom over, and just fill the gap between the top/deck and hull ?

or is this another 'failed' one ?

I don't believe this is a failed one coz if you see the part behind the engine itself, it seems to be one piece (the bonding intact). Both sides seem to have caulking inserted.

I wonder if this is just the splashwell top bonded on here as Chewy suggested and nothing structural?