NORCO GRP LTD

Marine products form the core of our output at Norco. Currently around 1250 marine parts per month are finished, a figure which is growing steadily with company expansion. We are a major supplier of grp products to the marine industry, with customers including boat builders Aquastar, Lewmar and Williams Marine.

Our main client is Sunseeker, one of the largest manufacturers of motoryachts in the world. Sunseeker has been with us since establishment in 1985, and named Norco as Supplier of the Year in 2004 at the Southampton Boat Show.

CONTACT NORCO...

By Phone: Within the UK: 01202 623934 From outside the UK: (International call prefix) + 44 - 1202 - 623934

By Fax: Within the UK: 01202 621940 From outside the UK: (International call prefix) + 44 - 1202 - 621940

By Email: Click on the following email address to email Managing Director Mark Northey direct: m.northey@norco.co.uk

By Post Norco GRP Ltd 33 Holton Road Holton Heath Industrial Estate Holton Heath Poole Dorset BH16 6LT UK

Norco manufactures GRP products for every part of a boat from bow to stern, inside and out.

Hand Laid Glass Reinforced Plastic (also known as GRP and FRP) is the prefered method of production for 70% of our customers and we have been producing products in this way for 20 years.

Hand lay-up moulding may be used for the production of GRP parts of any dimensions.

This method is generally limited to the manufacture of parts with relatively simple shapes that require only one face to have a smooth appearance (the other face being rough from the moulding operation). Norco GRP however are specialists in double finished surfaces and grp split moulding.

It is recommended for small and medium volumes, for which the investment in moulds and equipment are not very high.

The GRP contact moulding method consists of applying successively onto a mould:

a release agent

a gel coat

a layer of liquid thermosetting resin

a layer of reinforcement (glass, aramid, carbon, etc.) in the form of chopped strands mat or woven roving, and to impregnate the reinforcement by hand with the aid of a roller or a brush. This operation is repeated as many times as there are layers of reinforcement, in order to obtain the desired thickness of the structure.

Laminates are left to cure under standard atmospheric conditions.

Main advantages of finished GRP Laminates are:

Readily available materials

Widely used for many years

Low cost tooling, if room-temperature cure resins are used

Wide choice of suppliers and material types

Higher fibre contents, and longer fibres than with spray lay-up

Some examples of the use of grp mouldings...

large flush deck hatches have consistently proved difficult to attain and man-size hatches have been mostly cast aluminium.The hatches tended to rely on poor gaskets, had locking handles which leaked and the alloy coroded in the salt water.

To solve the problem, manufacture a range of flush GRP deck hatches, supplied with a perimeter drain gutter to take away the water plus a substantial neoprene gasket.

The lid/cover can be hinged or drop-in and is retained by heavy screw down storm clamps. The finish can be nonslip.

GRP Custom Mouldings -

Have you amaged an unobtainable part?

If your boat or yacht has suffered damage to a part such as an engine cowling, radar arch, locker lid, bathing platform and a manufacturer's replacement is not available, we will match the damaged part and build a new one for you.

Our craftsmen have constructed wheelhouses, shelter decks, hatches, bait boxes and numerous other mouldings, and can produce a quality polished finish when required.

YACHT SURVEYS...Scope of a Survey on GRP Vessels...

Hull or Deck

Some Common Defects

Osmosis

Stress Cracking

Bonding Web Failure

Deck Delamination

GRP HULLS

The exterior and interior surfaces are examined where accessible. Sample areas of antifouling are removed to expose the gelcoat, but protective epoxy paint schemes are not removed unless either they are already flaking off or if the Owner gives specific permission.

The yacht gelcoat surface is examined for the presence of of osmosis-related deterioration such as blistering, fibre-end blistering, and wicking.

The moisture content is measured with both Sovereign and Tramex meters, because they read to different depths. A raised moisture content is not necessarily evidence of osmosis, and by itself is not a sufficient reason to recommend an osmosis repair.

If a yacht hull has a protective epoxy scheme, it may not be possible to obtain representative moisture content readings until it has dried, typically taking about 7 to 14 days.

That rules out holding in slings over lunch-time, the usual cost-effective way of surveying GRP hulls. Alternatively, the coatings can be scraped back to expose the original polyester gelcoat, but permission may not be forthcoming and such patches are difficult to repair effectively.

The hull is examined for stress cracking, and in the case of motor vessels with sharp-angled spray rails, antifouling may be removed to check for cracks along the rails and at other high-load points.

The hull is hammer-sounded below the waterline to identify any delamination.

The hull above the waterline is inspected for cracks and repairs, and is selectively sounded with a plastic mallet for delamination.

The interior boat hulls are examined where exposed or through readily-removable traps. Apart from the internal surface of the hull itself, the reinforcement members such as bulkheads, frames, floors, stringers and engine beds are surveyed with particular attention to the state of the GRP webs that attach them to the hull.

GRP DECKS

The exterior surface is inspected for stress cracks, the state of the gelcoat, repairs etc. It is lightly hammer-sounded and checked for movement or creaks to determine the state of the sandwich core.

The underside of the deck is visually examined where accessible, as is the joint to the hull.

SOME COMMON DEFECTS IN GRP VESSELS

Osmosis

The term 'osmosis' is loosely used to describe damage to a polyester hull by water vapour penetration. The damage is caused by the hydrolysis of the laminate materials in water. There are too many different types and symptoms to detail here.

It is a relatively common problem, although less so now that the superior Isophthalic resins have been employed since the early 1990's. Until then, some osmosis could be expected at five to ten years of age. In its early stages, some deterioration is very unlikely to weaken the hull to the point where it is no longer fit for the designed purpose.

As the repair process is more or less the same regardless of the nature and extent of damage, it is in my view reasonable to defer repairs until they are essential.

A raised moisture content does not necessarily mean that a yacht has osmosis or will go on to develop it - it is only one of several factors which have to be taken into consideration.

In very bare outline, if a yacht has significant structural deterioration because of blistering etc, the industry-repair involves removing the gelcoat and any damaged laminate below the waterline and to about 4" above, cleaning and drying the laminate, and then applying a protective coating scheme of solvent-free epoxy resin.

Partial or local repairs are seldom successful in the medium or long term. One of the leading manufacturers of the epoxies used recently stated that their predicted life was no more than 8 to 10 years.

I have therefore formed the opinion that the only long-term solution is to reinforce the prepared hull with one or more glass cloth laminates laid-up with epoxy laminating resin, before applying the protective coats. That will replace the strength lost both to the hydrolysis and the removal of the surface glass during preparation. It provides significant extra toughness and also thickness of epoxy resin.

While relamination adds to the cost, it seems reasonable to do the job once, properly, rather than twice - when the requirement for relamination will be beyond doubt.

Whatever you do, do not grind off the surface blisters and then repaint. That does not address the fundamental problem, but only deals with the outward signs. The hull will deteriorate rapidly after such abuse.

Stress Cracking

Some hairline cracking may be expected in the gelcoat almost anywhere. Frequently it does not penetrate into the glass reinforcement: the gelcoat is more brittle than the glass laminate, and so cracks more easily.

Some may date from mould release. Below the waterline, cracks should be sealed to protect the glass from water penetration, but above the waterline, and in the deck, repairs may be more obtrusive than the cracks. However, you need a surveyor to determine which are significant and which may safely be left unrepaired.

Stress cracks are particularly common along the chines and spray-rails of fast powerboats. That may well be a sign of excessive flexing when pounding in a seaway.

The sharp corners necessary to produce good handling are difficult to back-up with the glass reinforcement during build, and cracks may develop in the voids. In some cases, additional reinforcement may even be needed inside the hull, perhaps by way of frames or stringers. These cracks always need careful inspection and are relatively costly to repair if extensive.

Failed Bonding Webs

It is quite common in older boats to find some failures in the GRP webs used to attach plywood bulkheads, frames or stringers to the hull shell. Unless these failures are very extensive, which may signal either gross misuse or some more extensive structural defect, they are not normally a significant problem and are usually quite straightforward to repair.

Deck Delamination

This is mainly a problem for older boats.

Most GRP vessels have sandwich decks, having an end-grain balsa or foam core between the two laminates. That is intended to keep the weight down while maintaining stiffness. If the bond between the GRP and the core breaks down, the deck will become flexible and spongy under-foot, and will probably creak when walked over.

Some such weakening is to be expected in older boats. Small areas may not be a problem, but larger areas need repair. That can sometimes be achieved by injecting epoxy resins, but if water has entered the sandwich that will not work.

Delaminated decks are in many ways more difficult to repair than osmosis, because the repair site is inaccessible. It is almost impossible to open up the deck surface and reinstate it without it showing in the non-slip pattern or other such detailing. Repairs can be done from the underside, but again there are problems of access and the difficulty of applying resins, core material and glass 'upside down'.

A small amount of delamination is unlikely to make the yacht unseaworthy, but any damage around such things as mooring cleats, chainplates and so on does need careful consideration.

Variable Temperature Moulding carbon epoxy prepregs have helped British marine glazing manufacturer Trend Marine Products of Catfield, Norfolk, UK, to develop a line of light and strong sliding sunroofs that have opened up new design possibilities for a growing number of production boatbuilders.

The demand for open-top yachting has been in great demand in recent years. However, boat owners want the security of being able to close cabin roofs quickly when the weather takes a turn for the worse while still taking maximum advantage of whatever natural light is available. As the fashion for open express cruisers continues to demand ever-larger production/semi-production boats, the requirement for larger yacht sunroofs has placed increasing technical demands on boatbuilders and their suppliers.

Initially, for Trend, the main problem was to produce an unsupported, gently curved structure that would carry a large sheet of heavy safety or laminated glass. However, the structure had to be light enough so that it didn't raise the boat's centre of gravity, while also being rigid and slim enough to slide away neatly out of sight when the roof was open. Moreover, it had to do all of this without encroaching on the available headroom.

Robin Thatcher, Trend's Technical and Sales Director, says, "Our sunroof business has been gathering pace - almost to a drum beat. Sunroofs are the fastest-growing part of our business now. In units, we were making about 150 a year, but with our increased capability on the bespoke carbon fibre side, we are now looking at producing 200 or 300 roofs a year.

This business now accounts for between 5 to 10 per cent of our turnover." Furthermore, Mr. Thatcher states, "Sales of all Trend products are now approaching £20 million a year".

On the yacht sunroofs side, the lengthening list of customers includes all of the UK's largest powerboat builders as well as Spain's Rodman and France's Bénéteau group, where it now supplies roofs for five boat lines.

More recently, motoryacht builders in North America have also become customers for Trend's yacht sunroofs. These include one major US production boatbuilder that is due to launch a new powercruiser model later this year.

This will have a large sheer glazed, double curved and tinted sunroof mounted on a light carbon composite grid.

The single most important factor in Trend's success with sunroofs has been its ability to mould relatively large, yet light and strong structures in carbon fibre composite.

Trend Marine Products Ltd

Catfield

Great Yarmouth

NR29 5BG England

Tel : 0845 068 7363

Fax : 01692 582550