How to use boatbuilding skills to fix a lorry!
HF Marin AB is our distributor of WEST SYSTEM® products in Sweden, but in addition to supplying a wide range of boatbuilders, HF Marin also provides epoxy to a leading truck repair workshop.
When a lorry was brought in with side panel damage, the workshop thought it would be interesting to share photos of the repair process. The methods are very similar to those used to make a boat’s hull equally strong again, but also make the damaged area completely disappear.
“The workshop didn’t feel that polyester resin would make an entirely invisible or smooth repair,” explained HF Marine’s MD Krister Bewert. “They decided to use WEST SYSTEM epoxy instead because it has very strong adhesion properties, but – perhaps more critically – it has virtually no shrinkage. Polyester can shrink by as much as 2% in volume when cured, and this often causes small cracks to open at the edge of the patch, but epoxy remains pretty much the same. This means a repair will be very stable and long lasting.”
Krister has forwarded the body shop’s repair sequence pictures you can see below, and points out that the thin nature of the wall of the truck meant that the usual grind back ratio of 12:1 wasn’t really possible in this case.
“Once the damaged section had been cut out, the workshop ground back the edges of the damage to make a taper for the cloth and filler to bond to,” he said. “You are taught that on boats, this should be quite shallow, say a gradient of 12:1 for the greatest area of adhesion, but this clearly wasn’t possible on such a thin wall.”
The removed section was used as a template, and the area behind the wall stabilised with epoxy and reinforcing cloth.
“The inner material was glued with a mix of WEST SYSTEM 105 resin and 205 Fast Hardener with 406 Adhesive Filler. Some layers of 175gsm cloth were used as backing and support before the two tapered surfaces were filled and faired using 105/205 epoxy hardener mixed with 410 filler additive. As you can see as the sequence ends, the whole area of damage has completely vanished.”
HF Marin also supplies a wide range of other well-known marine brands, and has just taken delivery of the classic wooden yacht Princess Svanevit for a major restoration. The Swedish R12 class yacht was built in 1930 and had recently been berthed in the Hamble River on the UK’s South Coast before being relocated back to Sweden earlier in 2018. A project group has been started to fully restore the yacht and launch her in 2020. We plan to bring you the story of her restoration as it unfolds.
Visit HF Marin AB’s website to find out more about our distributor: www.hfmarinsweden.se
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