Stress Fractures On Coachbuilt MH's?

Can anyone give me advice regarding how common stress fractures are on coachbuilt bodys? noticed at recent MH shows we have attended that a few showed signs of this on corners and along the lower sides (only way I can describe it is lots of very fine hairline cracks?) firstly what causes these in the first place? can they be repaired successfully and if so how good is the cosmetic side of the repair? generally how common are these?

CC

Hi CC,

Tried many times to cover-up/repair stress cracks on boat cabin tops and caravans, without success ... always came back later, I hope someone else has had more luck and lets us all know

Brian

Hi CC.

Have noticed that the older monocoques have thick fibreglass, they do get some stress cracks but not many and they appear to reach a point and stop. Some of the newer vans have a thinner Perspex fibreglass reinforced bodyshell. They seem to craze rather than crack but keep on going. I'm no expert, these are just my observations, but consider.



Good luck getting your new van. Whisky.[You must be registered and logged in to see this image.]

Thanks guys.....

I was reading a thread over on the darkside (MHF's) which was suggesting this is fairly common or at least that was the impression I was getting We spoke to a dealer today about a Nuevo and asked for a verbal walk around on the vehicle, the only thing they could find was a stress crack on the rear corner which in their words is only minor but that they would put into the workshop and get it sorted, they claim that they frequently have vehicles in for this type of cosmetic work and it's easily rectified?

As said earlier Ive seen this crazing and cracking on MH's at shows, also a Sherbourne we looked at a few months back had this quite badly behind the drivers side panel so just wondering if this kind of thing is as common as it seems to be?

Hi again CC,

Quote ; 'this type of cosmetic work and it's easily rectified', ?? oh really ... i'm sure some people with very expensive boats will be pleased to employ them !!
Brian

In fairness they did say it's barely visible, so probably not quite as bad as you are imagining deckie On our budget there may well have to be compromises, the price is within budget (just) and the miles suggest it's not even run in.. so just exploring options really

Getting back to stress cracks, the thread I was reading on MHF's was talking about Autocruise who do these kind of cosmetic repairs at the customers house rather than take them in to the workshop for repair, which would run in line with what they are saying

Hi CC,

Sorry ..... was past 'old git's' bedtime and taking 'the' 'T' shirt off.

Good luck with your new AS hunting

Brian

Brian, think you too should get yourself one of these....

[You must be registered and logged in to see this link.]

CruizingComet wrote: Brian, think you too should get yourself one of these....

[You must be registered and logged in to see this link.]

Hi CC,

Mrs Deckie says 'Thanks' .... (think it was sarcasm )

She has now got to spend about £80 for my Chrissy Pressy

Can't wait

Brian

Stress fractures on external faces of GRP mouldings is very common & its almost impossible not to have them somewhere, its only the cosmetic gel-coat that cracks, almost never the structural glass/resin underneith.
GRP panels will readily accept 'drumming' type of flexing ( in-out ) , but not torsional, like on door/window openings in the corners etc. If, for instance the body was TOTALLY rigid on the chassis, then all would probably be ok, but unfortunatley , a certain amount of 'twist or droop' always exists, thus encouraging cracks to grow, usually from internal corners.
Polyester gel-coat is extremley brittle,thats why it'll crack, I know a little bit about this as in my little buisiness, we've made thousands of GRP moulds & components over the last 22 years, ok so they're only a metre or so in size, but the same conditions & results apply.
In extreme cases, many close to each-other cracks can allow a chunk of gel-coat to fall away, exposing the laminate undernieth, it can be 'undercut' & a matching-colour gel coat can be puttied-in, rubbed down, polished & made almost invisble, but the cracks WILL more than likely come back!

Thanks modelman, seems inevitable with coachbuilts that most suffer with this at some point in their lives, so your advice is reassuring

deckie wrote: ... i'm sure some people with very expensive boats will be pleased to employ them !!

And some of us with cheap ones as well!

The good news for MH owners is that whilst the fibreglass may "craze" it shouldn't affect the structural integrity like a boat hull where the crazing allows the dreaded osmosis (a situation that causes the gel coat to pock) which in turn can lead to de-lamination (a situation where the resin starts to part company with the glass fibres) which severely reduces the physical strength of the GRP.

In other words, on a MH it is probably more a cosmetic problem rather than a structural one.

My boat Karra has had 36 hard years being sailed on a regular basis and she is still structurally sound so I wouldn't worry too much about a bit of crazing on a MH.

Best regards,

Dutto

Had a stress fracture on 21 bourton on corner of front window, back to factory, all good now.

The penultimate post on this thread was 12 years ago. CC is the only contributor still active on the forum.

The stress fractures on my new AS coach builts were remedied satisfactorily by the factory but several years later the fact that the area had been sprayed over was much more obvious than the micro crack would have been and, as Modelman said, the issue was cosmetic not structural.