DECK COVERINGS

Your metal deck will need some form of treatment to provide a non-slip footing as you move about the boat. The least expensive treatment is to apply a special paint that contains grit. Many metal boats use this paint-grit combination, and provided it’s installed in a proper manner it can look attractive and it does work well in practice. When you’re installing a painted non-skid surface, you should leave small borders around various fittings and alongside the cabin and inside the bulwark and so forth—places that do not have grit added. Be careful how you lay out these un-gritted areas, though, as you don’t want to leave skid-inducing shiny spaces in high-traffic areas. If the un-gritted areas are no more than 1 1/4 inches (320 mm) wide around any feature, you shouldn’t have a problem. You can always fill in any problem spaces with gritted paint.

   The next step up in cost and appearance is to use a deck covering like Treadmaster or a similar product. These coverings are composite materials formed in patterned sheets suitable for gluing to your deck. When laying out this covering, you should use a similar pattern as suggested for painting decks with gritted material. Available in a range of attractive colors, these products are bonded to your deck with special glue.

   The diamond pattern on some of these sheet products can be hard on your bottom and other areas that may come into contact with the deck. So don’t use it on cockpit seats or similar locations. There are alternative, less harsh patterns that can be used where a user-friendly, non-slip surface is required.

   Personally I do not favour timber-laid decks on metal boats. If you plan to keep your boat longer than, say, 10 years, then you can expect have some problems if you install a laid timber deck on a steel boat. Problems with laid timber decks are not restricted to metal boats; many fiberglass boats that are manufactured by the most reputable companies also have problems with the laid timber decks once the boat has reached a certain age. The main problems are caused by the breakdown in the caulking materials. The caulking will develop hairline cracks after a few years and this allows water to seep through to the metal decks below. If you are installing or renovating a teak deck, under no circumstances stint on the quality of this caulking material.

   Recently a simulated teak deck material has become available and this plastic-based (for want of a better description) material will be worth your investigation. It closely resembles teak and is laid in a similar manner, so check out this material before you consider a wooden deck.

However, some of you will settle for nothing but a laid wood deck. You may be surprised to learn that there are species of timber other than teak that are suitable for laid-plank decks. In Australia, beech is widely used, and in the United States quarter-sawn Douglas fir has been used for the same purpose. Nonetheless, teak is the premier material and the one you are most likely to be using to finish the decks of your metal boat in style.

   After you decide that a laid deck is for you, the next step is to determine if you’re going to have a “wannabe” teak deck or the real thing. The “wannabe” type is usually 1/2 inch (12 mm) or less thick, and in most cases it will not do justice to your boat or to the craftsmanship needed to install any laid deck. A “proper” laid deck should have planks of at least 5/8 inch (15 mm) and preferably 3/4 inch (20 mm) minimum thickness.

   There are many ways to install this deck on a metal boat but all will involve setting the planks in some form of bedding compound. Again, we can take a lead from Dutch builders who have been successfully installing laid decks on steel and other metal boats for a long time. The outer planks will need to be fastened to the steel deck itself. The inner planks may simply be set in the bedding compound and caulked.

The regular planks should be about 1 3/4 inches (42 mm) in width. The outer and inner covering boards, king plank, and other featured planks around hatches and vents will be wider, usually 4 to 6 inches (100 to 150 mm), depending on the size of the boat and the way the deck is installed. The outer covering board is a misnomer in this case, as there should be a space between the edge of the teak covering board and the edge of the deck to create a channel for water to run alongside the outer teak plank and on out through the scuppers.

   The bulk of the fore-and-aft planking can be laid in several ways. It can follow the outer shape of the hull, generally known as the "swept" style of fore-and-aft planking, or it can follow the line of the cabin sides, or it can split the difference. The main effect of these various methods is the way the planks need to be “nibbed” into the outer and inner covering boards and king plank. It’s also possible to lay the deck in a herringbone pattern; this has been done on more than one of our designs, but we prefer longitudinal planking that splits the difference. (Naturally, this is the most expensive form of planking!)

ALTERNATIVE DECKS AND SUPERSTRUCTURES

Although there are arguments for building a boat using all steel or all aluminum there are many reasons why some of you may prefer to take a different approach. If your metalworking skills are limited, and you have more experience with working in timber, you may consider a timber deck and superstructure.

PLYWOOD AND TIMBER DECKS AND SUPERSTRUCTURE

A good reason to install a plywood deck and superstructure on a small steel boat is to keep weight down. If you take the timber-and-plywood deck option, you’ll need to select a point where you make the transition from metal to timber. The choices are to have the hull built in metal and install a margin plate welded to the inside or sheerline of the hull, where the deck will join the hull. The margin plate will take the place of, and be installed in the same location as, the deck stringer in an all-metal boat. Another alternative is to have the hull and complete decks built from metal and include an up-stand in metal to accept the timber superstructure, located all around the inner edge where the cabin sides will be installed. In both cases, the timber and/or plywood would overlap the metal so that surface water or other moisture would be less likely to get between the metal and timber to cause corrosion.

   If you’re planning a laid teak deck, it may influence your decision. A teak deck is much easier to install over a timber and plywood deck than it is over a metal one. There’s no doubt that a timber deck and superstructure is a beautiful sight from both without and within. You pay a price, though, at least for the beauty of the exterior. The maintenance requirements of external timber and plywood will be far greater than if the items were constructed from metal. This applies not only to large items, as in a pilothouse or cabin structure, but extends to timber hatches, handrails, cap rails, and rubbing strips. These items, when built in timber and finished “natural,” do improve the appearance of any boat, but the maintenance requirements can be horrific.

   After you’ve installed either the metal margin plate to the hull, or the metal up-stand to the inner edge of the metal decks, then you should install a timber carlin to allow you to carry on the remainder of the construction in timber. You should rebate this timber in such a way as to discourage any water from becoming trapped in the joint and later causing rot in the timber. It’s imperative that you make a watertight join between the timber and the metal.

   Deck beams may be of timber or metal. In the case of a metal deck, then L- or T-metal deck beams will be used; however, in the case of an all-timber-and-plywood deck and superstructure, you may choose either metal or timber beams. If you use metal beams with a plywood deck, make sure you place the flange upwards. This is opposite to what you would do for metal decks. The flange will provide a ground and will allow you to screw the plywood to the beams from underneath. Timber beams can be laminated or sawn, but laminated beams are recommended.

   This is a good time to mention that you should use epoxy-based adhesives throughout the construction of any plywood decks and/or superstructure. Where the plywood is attached to the metal margin plate or up-stand, a suitable bedding compound will be used rather than an epoxy adhesive. An epoxy system such as the West System should be used to saturate all of the timber and plywood parts used to build your decks and superstructure, but not on teak decks.

   It’s usually preferable to laminate the decks and cabin tops from more than one layer of plywood. If your deck calls for 1/2-inch (12 mm) plywood, then use two layers of 1/4-inch (6 mm) each. If the recommended thickness is 3/4-inch (20 mm) plywood, then use two layers of 3/8-inch (10 mm) or, better still, three layers of 1/4-inch (6 mm). Use either bronze nails or staples to apply pressure to the glue lines until the adhesive has cured.

   If you’re installing plywood decks, one labor-saving tip is to paint the underside of the first sheet before you install it. Make sure you don’t paint the strips where the plywood will be glued to the beams. Fit the panels first, and, from underneath, mark where the beams will fall and where the plywood rests on the other timber supports. Now mask off those areas on the plywood and paint the rest.

   There are several methods of finishing off your plywood decks and cabin structure but no matter how you do it, we recommend that you give the entire area a coat of fiberglass cloth in epoxy resin. Don’t use polyester resin for fiber glassing over plywood or timber, always use epoxy resins. The only place for polyester resins is in the building of an all-fiberglass boat.

   When you’re using epoxy resins and adhesives, make sure that you follow all of the safety precautions recommended by the manufacturers. When handling these materials, always wear protective gloves and use protective skin creams. Keep in mind that epoxy stays toxic for several days while it’s curing. When you’re building timber and plywood decks and superstructures, you’ll find the Gougeon brothers’ West System book a good source of information. See Appendix 1 for more details.

ALUMINUM DECKS AND SUPERSTRUCTURE

When you build an aluminum hull, you’ll almost certainly install decks and superstructure of the same material. The benefits of installing an aluminum deck and superstructure on any metal boat include less weight up high, where it’s detrimental. Aluminum is easier to form into small-radius sections such as those used on the corners of cabins, pilothouse fronts, coamings, and similar areas. A little forethought and a considerable amount of welding can be saved by combining seats to backs and so forth.

   The aluminum decks and superstructure are somewhat more removed from the seawater elements than the hull is, and it’s easier to avoid some of the electrolytic problems suffered by boats built completely from this material. The practice of installing aluminum decks and superstructures on steel hulls has been well proven over the past 30 to 40 years, so you can consider it an acceptable boatbuilding practice.

Aluminum decks and superstructures fitted to steel or copper-nickel hulls will need to have the different metals isolated from one another to prevent electrolysis. There are a number of methods you can use to achieve this isolation. The first that comes to mind is to insert a neoprene strip between the two different metals and bolt them together with bolts housed in nylon sleeves and nuts that are isolated with nylon washers.