stress cracks in gelcoat

hadd · 29 December 2009, 15:54

I bought a new rib in September 2009, I have been out on it once and just found some stress cracks at the back of the transem, each side of the engine. Is this due to the engine being to big ? ( 70 hp on 5.2 meter rib ) or would it be a design fault ?. Advise would be of help.

two stroke mick · 29 December 2009, 15:59

People will need to know more. What type of rib, type of engine and the max permitted engine size/weight

TSM

CJL · 29 December 2009, 16:00

It's not ideal on any RIB, new or otherwise.

If it's still in warranty take it back and get it seen to (assuming you've got the right size engine on the transom).

If you can't do that it's unlikely to be structual so I'd get the cracks filled and keep the water out.

As TSM say's more info or a pic would help.

CJL

hadd · 29 December 2009, 16:07

Quote:

Originally Posted by two stroke mick

People will need to know more. What type of rib, type of engine and the max permitted engine size/weight

TSM

The size of the engine 70 hp evinrude RNLI , The boat is suppose to be able to take an engine upto 90hp.

Boat is a Seapro.

Resque · 29 December 2009, 18:34

Here they say its only a 70hp on a 520 sport http://www.seaproboat.co.uk/ribs.php Scroll a bit down to the spec sheet....

They also say at their site they give 3yrs warranty...

chewy · 29 December 2009, 20:54

Should be ok with the ex RNLI 70hp as they are showing the same engine fitted on their site.

biffer · 30 December 2009, 08:58

the way transom's are built you shouldn't get stress crack's on it, i'll explain, stress cracks appear when 1. the gells to thick and 2. the structure the gells on flex's, the way a normal transom is laid up there should be no movement in it, you may find crack's around the edge of a transom but across the face is unusual

Cookee · 30 December 2009, 09:25

Does anyone know where they are made?

hadd · 30 December 2009, 10:42

Quote:

Originally Posted by biffer

the way transom's are built you shouldn't get stress crack's on it, i'll explain, stress cracks appear when 1. the gells to thick and 2. the structure the gells on flex's, the way a normal transom is laid up there should be no movement in it, you may find crack's around the edge of a transom but across the face is unusual

Hi, the cracks looks like a spiders web on each side of the engine ,i took some pic,s of them but don,t show up very well, i'll take the rib in to the dealer next week and see wot they got to say thanks.

hadd · 30 December 2009, 10:48

Quote:

Originally Posted by Cookee

Does anyone know where they are made?

I think America

biffer · 30 December 2009, 12:29

are they crack's or maybe lines that were in the mould when it was layed up, what i'm asking is were they always there or have they appeared, if they have appeared get a small screw driver and tap all over the transom and tell me if it sounds hollow in some places

hadd · 30 December 2009, 16:57

Quote:

Originally Posted by biffer

are they crack's or maybe lines that were in the mould when it was layed up, what i'm asking is were they always there or have they appeared, if they have appeared get a small screw driver and tap all over the transom and tell me if it sounds hollow in some places

They are little lines like a spiders web they span about 4in round, iv tap the transom and that seems solid, i don,t think the lines were there before i would of seen them, il take the rib back to the dealer ,he as a test rib with bigger engine than mine i will check that to see if thats the same cheers.

Downhilldai · 30 December 2009, 17:20

Quote:

Originally Posted by hadd

...il take the rib back to the dealer ,he as a test rib with bigger engine than mine i will check that to see if thats the same cheers.

If the test RIB is the same, then don't get misled into believing 2 wrongs make a right.

Top banana · 30 December 2009, 19:01

Quote:

Originally Posted by hadd

Hi, the cracks looks like a spiders web on each side of the engine ,i took some pic,s of them but don,t show up very well, i'll take the rib in to the dealer next week and see wot they got to say thanks.

could they have occured by overtigtening the engine bolts to much.

hadd · 30 December 2009, 19:44

Quote:

Originally Posted by Top banana

could they have occured by overtigtening the engine bolts to much.

thats wot iv been thinking, the cracks,s are in line with the bottom bolts on each side of engine,the rib as had some work done on drain plug and engine by the dealer over the last few weeks and i know the engine has been off the rib cheers.

biffer · 30 December 2009, 20:06

Quote:

Originally Posted by hadd

thats wot iv been thinking, the cracks,s are in line with the bottom bolts on each side of engine,the rib as had some work done on drain plug and engine by the dealer over the last few weeks and i know the engine has been off the rib cheers.

this is what i was getting at by tapping with the screwdriver, if there were voids between the first layers of matt and the ply the crack's may have happened when they tighten up the engine bolts, if there were no voids you could tighten them bolts until they snapped they wouldn't cause crack's, there is a method of getting rid of voids but you have to do it quickly before the ply gets contaminated

hadd · 30 December 2009, 20:33

Quote:

Originally Posted by biffer

this is what i was getting at by tapping with the screwdriver, if there were voids between the first layers of matt and the ply the crack's may have happened when they tighten up the engine bolts, if there were no voids you could tighten them bolts until they snapped they wouldn't cause crack's, there is a method of getting rid of voids but you have to do it quickly before the ply gets contaminated

The ribs under 3yr warranty it can go back to the dealer if they done the damage they can sort it thank.