Cracks in transom - New boat

Matthew MacLean · 11 July 2005, 11:02

Just checking out my RIB tonight and found 2 small cracks in the transom. Cracks are in the corners of the cut out of the recess for the engine, one in each corner. They follow the profile of the cut out, are about 1 1/3 inches (35mm)long and 2 inches (50 mm)respectively and are located about 10mm from the top edge. Please see photos provided.

RIB is only 14 hours old. Engine was installed professionally. Have done some fair trips in it so far. A bit of rough choppy water. 2 fairly rough runs where it was all throttle work to stop the boat (passangers) taking a pounding.

Motor is a single 135 Hp 2 stroke (Evinrude). transom is rated for 140 HP, and have seen 140 4 strokes (weighing 30kg more) and routinuely twin 70 HP installation on the same hull coming in at 220kg , so weight should not be an issue. (motor is 190kg)

A visual inside the transom shows no cracks and no other stress lines show up on the hull else where. Trailer set up is good with rear rollers coming to within a inch of the edge of the transom.

Is this a problem or just acceptable stress relief?. I don't want to go back to the supplier unless I really have to as it will be a major warranty claim.

All help Appreciated

Matt

Scotty · 11 July 2005, 13:09

For what it's worth I would show the boat to the retailer and let him have the pictures. Document everything to him and keep copies. By the way do you know an engineer ?

Matthew MacLean · 12 July 2005, 09:27

Quote:

Originally Posted by Scotty

. By the way do you know an engineer ?

Yer, and as a kid I worked in a fiberglass factory makng boats

But I more than happy to get a second opinion from people who see this sort of thing every day.

This one has me concerned so I put it out there. Thinking most likely it is just cracking in the gel coat. Have forwarded the pics to the supplier, and will be taking the boat back to them shortly for evaluation. So hopefuly it'd nothing and they'll fix it and it will be never seen again.

Matt

codprawn · 12 July 2005, 11:33

Quote:

Originally Posted by Matthew MacLean

Yer, and as a kid I worked in a fiberglass factory makng boats

But I more than happy to get a second opinion from people who see this sort of thing every day.

This one has me concerned so I put it out there. Thinking most likely it is just cracking in the gel coat. Have forwarded the pics to the supplier, and will be taking the boat back to them shortly for evaluation. So hopefuly it'd nothing and they'll fix it and it will be never seen again.

Matt

I have read about quite a few others here with similar problems - as you said probably just cracks in the gel coat that will settle down sooner or later.

jwalker · 12 July 2005, 16:19

Quote:

Originally Posted by codprawn

..- as you said probably just cracks in the gel coat that will settle down sooner or later.

Nah.

Manos · 14 July 2005, 13:58

agree with JW

Cookee · 15 July 2005, 08:13

Quote:

Originally Posted by codprawn

I have read about quite a few others here with similar problems - as you said probably just cracks in the gel coat that will settle down sooner or later.

don't think so! You a boat builder now as well?

Matthew MacLean · 15 July 2005, 10:50

Thanks to the guys who added something constructive to this thread. To the last 3 posters, if you really want to display your extensive knowledge, suggest a but of detailed discussion about what can cause this/ advice on the problem, cause you really are not covering yourself with glory here.

Matthew

Pete7 · 15 July 2005, 11:00

Matt, take it back to the dealer. Then he can see there is a problem and fix it. If you don't:

1. The manufacturer will continue to assume everything is hunky dory.

2. Salt water will soak into the grp underneath.

3. The cracks may continue to spread further.

4. This may or may not be the first sign of a serious problem.

Ask the manufacturer / dealer to investigate the problem and come up with a solution.

Pete

Cookee · 15 July 2005, 11:07

Sorry Mathew, you're quite right, what I should have said is that cracks such as these should never be ignored, and as Pete said, get them looked at - to make a judgement from a couple of photos and some text is impossible, and anything anybody says without prior knowledge of problems with that make and model of hull is just guessing.

Quote:

I don't want to go back to the supplier unless I really have to as it will be a major warranty claim.

I think that's the only way to sort it out?

ribraff · 15 July 2005, 11:26

......has been cut down, capped and flowcoated, the flowcoat is basically gel-coat mixed with wax in Styrene to give a 'flowed' non-sticky surface.
What i find suprising is that the Gelcoat has a certain amount of flexibility in it which should be able to withstand this application.
Further investigation required i think.

Jono · 15 July 2005, 11:39

Quote:

Originally Posted by Matthew MacLean

Thanks ... To the last 3 posters, if you really want to display your extensive knowledge...
Matthew

One's a boat builder by trade, the other builds boats for "fun", both have more knowledge about these things than most of the rest of this board put together...

You'll find that their comments were given to indicate that some of the other comments by the "less well qualified" should be taken with a pinch of salt... take heed of their input and you won't go far wrong....

...and the other one of the last three posters?...

codprawn · 15 July 2005, 11:56

Quote:

Originally Posted by Cookee

don't think so! You a boat builder now as well?

Why don't you READ what I said!!! I was only commenting on what others had said on this forum in the past!!!

Whilst I may not be a boat builder I DO have a very good knowledge of engineering in general - know all about the spreading of stress cracks etc etc.

Fibreglass is a lot more brittle than plywood - it stands to reason the cracks could easily be just on the surface - as Rich says though cracks such as these can lead to water getting into the laminate causing all sorts of problems.

jwalker · 15 July 2005, 11:58

Quote:

Originally Posted by Matthew MacLean

To the last 3 posters, if you really want to display your extensive knowledge, suggest a but of detailed discussion about what can cause this/ advice on the problem, cause you really are not covering yourself with glory here.

Matthew, you're asking for help, don't get shirty.

It's impossible to tell why your transom is cracking, but it shouldn't be cracking. The remedy is obvious, take it back to the supplier.

What makes you think we want to display our extensive knowledge?

jwalker · 15 July 2005, 12:00

Quote:

Originally Posted by codprawn

Fibreglass is a lot more brittle than plywood - it stands to reason the cracks could easily be just on the surface ...

Pish.

codprawn · 15 July 2005, 12:09

Quote:

Originally Posted by jwalker

Pish.

Very technical answer - so you are telling me that the plywood transom is also going to have cracked in the same place??? Through all of those plies???

kitten · 15 July 2005, 14:37

STOP.

My Granny used to say " if you don't know what you are talking about shutup"
Ribraff why if the transom was cut and flowcoated did they bother to finish the top and not the rear face?

Codders with your prolific knowledge of stress how have you not noted the direction and location of the evident cracking as a clue to the cause?

I was going to ignore this thread when Cookee told me, as I was too busy making splitpoint drills with an anglegrinder (JW I concure they are the tool for all seasons). But now I will add my twopennuth.

In my humble opinion the transom is split on the interface between the moulded top return and what ever the builder has used as a filler/adhesive.
As the transom has bowed it has created tensile loading on this joint which has failed to some degree resulting in the visible damage.
This is possibly due to the over use of some form of bonding paste or air voids in behind. At the end of the day, no one can say for sure from a photo, and the only way I know of examining a build thoroughly is destructive.
Give the builder first chance to sort it but if it reoccurs (I'd take odds) then get it to a third party for a report.
At the end of the day Im sure that I may be spouting just as much rubbish as the rest of them as I only have a fuzzy photo and 20+ years expirience to base this on.

ribraff · 18 July 2005, 10:23

...we are dealing with fuzzy photo's here so it's all speculation at this point, it is my (humble) belief that a cut out was made in the transom for a particular engine shaft length, this of course will also cut down the deck liner, it has then been finished off with a capping of fibreglass, taped up and flowcoated. I don't think there is any need for your Grandma's quotes.

Let's try and be nice

kitten · 18 July 2005, 11:48

Rib Raff
tried to pm you, but your box is full.

ribraff · 18 July 2005, 12:07

......empty now.