Hi, my name is Mark... This is my first post on RIB Net. Hello all.
I worked at Yamaha Motor UK Ltd for 16 years, latterly being responsible for Marine Special Projects, where we fitted KeelGuard to RNLI Rescue Water Craft amongst a number of others. I recently decided to leave Yamaha to start my own business, and am now sole importer / distributor of KeelShield for UK & Eire (amongst other products).
I can add a few details that my assist Tim with his enquiry (and will try to do so without doing a sales pitch!)...
I supplied a 6' Black KeelShield to Rib 4 Macmillan in support of the fabulous work they were and are doing with a great Cancer Charity. I guess it is a KeelShield (rather than a KeelGuard) that is being referred to. I had a conversation with R4M about selling it to raise money for the charity. The RRP of a 6' KeelShield is £149.95.
Both KeelGuard & KeelShield are 5 inches wide. Visually KeelGuard and KeelShield have different profiles and are made from different materials. KeelGuard is made from a more rubbery material and KeelShield is made from a urethane. Both are available in a variety of lengths. Both benefit from fitment when the protection strip and boat are warm & dry (70 degrees ideally) - this both for flexibility of the strip and maximum adhesion.
Both products recommend pre-cleaning the boat with an alcohol before fitting - KeelShield insist on Isopropyl and nothing else (as other alcohol solvents can leave a film). From memory KeelGuard are not so insistant. The SR4 has strong chines right up to the bow, so either strip would be under more strain than if they were stuck to an "unchined" bow. Personal Watercraft also have strong chines and can have hull protection strips fitted, although I concede an SR4's chines are sharper & more regular. KeelShield recommend using a PU product such as Sikaflex to add extra strength and protection to the edge of the strip. When I was with Yamaha, we took the decision to do this with KeelGuard aswell after a few issues with lifting adhesive.
Regards length, in general, from under the U-bold / bow eye to the first full load bearing keelroller is recommended when used regularly on a trailer. The reason being that with a sticky keelroller on one side and a boat on the other, movement may be taken up by the hull protection strip, eventually potentially causing the adhesive to blister (a bit like going for a long walk in your wellies with only one pair of socks on...!). If being kept on a drying mooring then this may not be an issue. I'm not familiar with the full hull profile on the SR4, but theoretically, a KeelShield could be fitted to a RIB's full keel length. A personal watercraft has a similar changing hull profile to a pad, as the vee-hull changes to flat profile for the jet intake. I've never known a problem with adhesion in this area. The drain holes could certainly be an issue. Both products can be cut if required (don't use a saw as the dust will stick to the adhesive).
The KeelShield installation video may assist and can be found here:
My company has a facebook page which has various pics and images on it (most recently 8 photos from an installation of Kevlar KeelShield with C-Fury): https://www.facebook.com/specialistsmallcraft
If you decided you wanted to have a hull protection strip on your SR4, it certainly wouldn't be the most straight forward hull to fit it too. Ultimate adhesion would I think depend on the preparation, temperature at time of installation and fitting as much as the product. KeelShield is available from all good Dealers - Yamaha Dealers especially will know me. If they have a warm dry workshop, they should be able to fit it for you too if required.
Forum members will of course be able to advise you from their personal experience of course, but I hope this assists.