Reply
 
Thread Tools Search this Thread
 
Old 24 June 2003, 14:36   #11
Administrator
 
John Kennett's Avatar
 
Country: UK - England
Town: Brighton
Length: 3m +
Join Date: May 2000
Posts: 6,830
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
__________________

__________________
John Kennett is offline   Reply With Quote
Old 24 June 2003, 14:42   #12
Member
 
Country: Ireland
Town: Ireland
Boat name: Ally Cat
Make: Several
Length: 6m +
Engine: Several
Join Date: Oct 2000
Posts: 333
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
__________________

__________________
Stuart McNamara
Club Powerboat.ie
www.powerboat.org
Powerboat is offline   Reply With Quote
Old 24 June 2003, 14:46   #13
Member
 
Country: UK - England
Town: Blackpool
Boat name: To Exi
Make: new sib 4 man
Length: 8+ft
Engine: Mariner 4hp long shaft
Join Date: Nov 2002
Posts: 1,012
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.
__________________
www.eurocommuter.com
crazyhorse is offline   Reply With Quote
Old 24 June 2003, 15:13   #14
Member
 
Cookee's Avatar
 
Country: UK - England
Town: Salcombe, Devon, UK
Boat name: BananaShark
Make: BananaShark
Length: 10m +
Engine: 2xYanmar 260 diesels
Join Date: Mar 2003
Posts: 4,225
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.

__________________
Cookee
Originally Posted by Zippy
When a boat looks that good who needs tubes!!!
Cookee is offline   Reply With Quote
Old 24 June 2003, 18:08   #15
Member
 
Country: UK - England
Town: Devon. uk
Boat name: bananashark
Make: me
Length: 7m +
Engine: opti 225
Join Date: Apr 2003
Posts: 323
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.
__________________
kitten is offline   Reply With Quote
Old 24 June 2003, 18:19   #16
Member
 
Country: Ireland
Town: Dublin
Boat name: wizzard
Make: REDBAY
Length: 7m +
Engine: 225 optimax
Join Date: Sep 2002
Posts: 835
avon

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
__________________
www.dublinsislands.com

WHEN THE CAT IS AWAY THE MICE GO TO REDBAY..............
gavin is offline   Reply With Quote
Old 24 June 2003, 18:58   #17
Member
 
Country: Ireland
Town: Ireland
Boat name: Ally Cat
Make: Several
Length: 6m +
Engine: Several
Join Date: Oct 2000
Posts: 333
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
__________________
Stuart McNamara
Club Powerboat.ie
www.powerboat.org
Powerboat is offline   Reply With Quote
Old 24 June 2003, 19:05   #18
Member
 
Country: UK - Scotland
Make: HumberOceanOffshore
Length: 8m +
Engine: Volvo KAD300/DPX
Join Date: Oct 2002
Posts: 4,962
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.
__________________
jwalker is offline   Reply With Quote
Old 24 June 2003, 19:16   #19
Member
 
Country: Ireland
Town: Ireland
Boat name: Ally Cat
Make: Several
Length: 6m +
Engine: Several
Join Date: Oct 2000
Posts: 333
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
__________________
Stuart McNamara
Club Powerboat.ie
www.powerboat.org
Powerboat is offline   Reply With Quote
Old 24 June 2003, 19:21   #20
Member
 
Country: UK - Scotland
Make: HumberOceanOffshore
Length: 8m +
Engine: Volvo KAD300/DPX
Join Date: Oct 2002
Posts: 4,962
Ta.

JW.
__________________

__________________
jwalker is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -5. The time now is 00:20.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.