some-questions-answered

Our guide to buying a RIB

Here you can find out the answers to many questions relating to RIBs. Just click on on any question to reveal the answer...

reveal Is it best to have moulded decks?

Moulded decks look great there is no doubt about it, but with hard use over time stress fractures are inevitable. Further more gel repairs prove expensive and difficult on non slip areas.

Also, most modern moulded decks and stringers (floor bearers) use a foam sandwich technique. The use of foam sandwich with G.R.P makes for a light strong structure (used in aircraft construction for some time). While in race boats this is desirable as they are used in relatively calm conditions, in Ribs with ply stringers the weight of ply in these areas (below deck) adds to stability when the craft is subject to high winds at speed or when in vertical or horizontal positions. Also, if a foam sandwich becomes delaminated it is almost impossible to repair. Fixing into it also proves difficult if you wish to add extra deck fittings at a later date. Ply also has a draw backs, and that is the fact it can rot if not sealed or completely over glassed. Over glassed ply is also a lot harder to make look pretty.

If you are about to buy a Rib it is important to make sure you know a bit about where and the way the hull and deck are constructed and joined. Many Rib companies now farm mould construction out to countries where labour and materials are cheap, one big problem with this is although the overall product looks good, construction technique, and use of specific materials is nine times out of ten based on trust. Having worked for a company that went down this route I must stress buyer beware, I have first hand experience in rectifying the horrors that can exist below decks some examples of which include pallet wood stringers, fuel tanks that have undercut weld (i.e. fused as apposed to welded), hull and decks joined with brittle joining paste and the best one, sweet wrappers actually over glassed in the lay up. The best bet is to actually visit the workshop and even see your boat being constructed, a reputable company will have no problem with this and if they do you have to ask yourself why.

reveal What does the design category mean?

The Categories are as follows

CAT WAVE HEIGHT WIND FORCE
A - Ocean exceeding 4m exceeding f8
B - Offshore up to and including 4m up to and including f8
C - Inshore up to and including 2m up to and including f6
D - Sheltered Waters up to and including 0.3m up to and including f4

The RCD (recreational craft directive) gives builders a set of guide lines to categorise their craft into either A, B, or C craft. The directive became mandatory in June 1998 and it gives the EC the benefit of a single specification for new recreational boats. From a consumer point of view it is a step forward in the right direction regards to safety, as by law builders have to declare to conform to the criteria.

However, don't be fooled into a false sense of security by this. Unless your craft has been coded (i.e. been assessed by the likes of the MCA for commercial use) the CE plate is no guarantee that it is 100% safe for that category. Although someone's name will be on the declaration of conformity to state that it is, that is of little comfort if someone has been seriously hurt or worse. The regulations and testing are no where near as strict as that encountered in the motor industry.

Test the boat and if possible test it in bad conditions unless you are only planning on boating in sunny calm conditions and if this is the case I would question why you are buying a Rib in the first place. Don't think that little plate on the transom means the design works either, trust me there are many boats out there for sale that don't work or start getting erratic when they hit certain speeds.

Did I mention testing the boat!

reveal How are GRP hulls made?

Traditional lay ups are achieved by over lapping chop strand mats (CSM) and stitched or roven- wovings at the keel giving a double thickness. This again gives weight at the lowest possible point in the hull acting much like a sailing keel that helps keep the boat in an upright position. This also helps in an impact situation.

The best ribs will be manufactured using the best materials, check that the materials used comply with industry ISO quality standards and/or are Lloyds approved. Resins and gels vary greatly in composition and on a finished craft there is no visible difference other than the invoice. Cheap materials are usually only apparent on failure two days after the warranty runs out.

Most GRP Ribs are built in polyester resin of some type, some omit less styrene into the atmosphere and are also more user friendly to the builder but are in turn more expensive. Isophalic resins used in the first couple of layers of glass hugely reduce the risk of osmosis (the dreaded fibre glass disease) which is an important point if you wish to moor or berth the boat. Glass matting comes in many forms most commonly used is chopped strand mat (CSM) this is, as the name suggests, chopped strands of glass randomly bonded (often with emulsion) to form a matting. Although this is the main make up of most ribs, stitched or woven mats are essential to gain rigidity.

reveal Tubes. Hypalon versus PVC - which is best?

Most RIBS today are manufactured with Hypalon tubes, however a lot of the smaller sized Ribs aren't and the tubes are manufactured with PVC mainly to keep manufacturers and subsequently retail costs down. There has been many a debate and articles on this subject and in my eyes it has nothing to do with which has more tear strength or UV resistance, after all how good is the material if the glue which adheres the tubes together fails? In my experience of fixing many Rib tubes of both types I can tell you PVC glue breaks down very quickly in comparison with Hypalon. and when it does go on the seams it really is game over.

Another drawback to PVC is it is also far harder to repair as it requires more than ideal atmospheric conditions. However the tubes are only as good as the construction, just because the collar is Hypalon does not mean every thing is hunky dory in the tube department, as with resin make the glue is critical. Bostick make the best, if it's good enough for the R.N.L.I and the military it's good enough for me and my crew.

When tubes are constructed, the glued faces need to be prepped (i.e. scuffed/sanded) this ensures a proper bond. This is impossible to detect looking at a new rib. although this seems obvious if it does occur. If you have or are buying a rib check the baffles even if it's new, this will save you doing it at sea with granny or kids on board if you get a puncture. To do this, inflate the chamber to be tested and suck out the air of the adjoining chamber with a vacuum, leave for a few hours and check pressure.

Surplus glue on new ribs will not become apparent until exposed to UV light and once brown is a pain to remove so look closely otherwise your one week old boat will look ten years old. Also, check the strips that bond the tube to the hull are stuck without creases or bubbles and that the bow has sufficient bonding material, imagine kicking a football into a puddle then imagine a ton of boat behind it, we are talking extreme forces and when the bow gives up its down hill to the stern.

reveal What is the best seating?

Seating hasn't come on in leaps and bounds in design and in many cases has gone backwards. It is a very important factor when choosing a Rib and one that greatly influences you and your crew's safety. When you buy a car, getting an adjustable seat goes without saying, but when it comes to boats things aren't so straight forward.

Jockey seats or pods are of the astride type and have stood the test of time mainly because they work. Back rests on pods vary so make sure you have sufficient support with plenty of padding. When cruising in calm weather its nice to be sitting down although in rough seas standing helps reduce the risk of spinal compression to the lower back. Some builders offer the option of stand and sit seating which can work really well. I have also seen some companies using perches but these offer no support and do not allow the user to brace themselves at all. In all cases make sure the manufacture allows YOU to decide how far away they are from the console.

Based in Sidlesham West Sussex, Jcraft was founded in 2005. Director Jamie Dobson has been involved in the RIB industry for over 16 years and is an expert boatbuilder and repair specialist.

© Jamie Dobson, Jcraft Ltd 2017

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