If your vessel was designed for offshore use, your plans should indicate the size and location of the various hatches. If you’re the builder, the details of strength and suitability will lie in your hands. In the interests of safety, all hatches and companionways are best located on the centreline of the vessel. This is especially important for passagemaking vessels. In the event of a knockdown, an open hatch on or off the centreline can admit tons of water before it can be closed.
You should take some time in deciding where and when to fit hatches. Before you start making holes in your decks, you need to have a firm idea as to the exact layout of your accommodation. You can simply plate the entire decks and superstructure, leaving the main hatchway available for access, and lay out your hatches at a later stage. Always keep in mind, however, that these areas need to be carefully planned and strongly constructed, especially in long-distance sailboats and power cruisers. The hatches that cover the openings in your boat may be called upon to withstand tons of water being dumped on the deck. Don’t treat them lightly; they need to be as strong as the hull.
About the only places in which a steel boat can leak are around the hatches and other openings. It’s important to construct and fit these hatches so that they are absolutely watertight. Strong hinges and closing devices are a must. There are many cases where boats have been seriously damaged and lost through the fitting of inferior hatches. Combining safety with liveability, it’s best to fit hatches with hinges on both the forward and the after edges.
COMMERCIALLY MADE HATCHES
Deciding whether you will make your own hatches or use commercially made ones may be a matter of economics. Careful shopping can often reduce the prices to an acceptable level. Professionally manufactured hatches may add a nice finishing touch to your otherwise self-built boat. Most commercially made hatches will be manufactured from marine-grade aluminum.
Unless you have your decks and superstructure built out of the same material as the hatches, you’ll need to isolate the hatches from the metal decks. A good commercially made hatch will have a precision-cast body of high-tensile alloy that will not corrode in the harsh marine environment. Tinted glazing is preferred, and it must be capable of taking the weight of more than one person and able to withstand the force of a breaking wave without deforming or breaking. Larger hatches should have three hinges that have been cast as part of the body of the hatch. To ensure water tightness under adverse conditions, a hatch that uses a neoprene O-ring seal is preferable to one that uses soft rubber strips. The neoprene is far superior to the spongy type of rubber seal and it will not deteriorate as quickly; also the O-ring neoprene seals are more resistant to sunlight.
MAKING YOUR OWN HATCHES
If you decide to build your own hatches, you can save a some money. It may be possible to construct them from materials you would otherwise throw away. We recommend that you build your hatches of steel, aluminum, or fiberglass. Timber and plywood hatches require considerable maintenance and, if of insufficient strength, offer a weak link in the security of your boat, so if you choose timber, make them strong. On the other hand, timber hatches and skylights can give a metal boat a touch of warmth, so if you’re prepared for additional work, both during and after installation, then timber hatches may be worth considering.
Metal deck hatches can be built easily with inner and outer coamings. You can weld the coamings directly to the deck, making sure you’ve installed either deck beams or intercostals (or both) to reinforce the deck plating from below. You can install the reinforcing beams from underneath after you’ve cut the aperture for the hatchway.
Metal Hatches
Obviously, it’s best to construct the hatches from the same material as the decks and superstructure. You’re more likely to have these materials on hand, and there will be no additional corrosion problems caused by mismatched materials. Arranging rounded corners on your hatches shouldn’t present you with any problems as all metals are capable of being formed into, say, a 3-inch (75 mm) radius. If you build your own hatches, some of the money you save can be invested in extra-thick acrylic-sheet glazing. Make sure it’s set in a suitable sealant and bolted in place with an adequate number of fastenings.
Metal hatches can be built with inner and outer coamings; this arrangement is like a box made with a fitted lid. The inner box that acts as the coaming can be welded directly to the deck around the cut-out you’ve created in the deck or cabin top. The height of the inner coaming can be from 2 to 6 inches (50 to 150 mm), and higher in larger vessels. The hatch top can have sides of 2 to 3 inches (50 to 75 mm). The top will look best if it’s cambered similar to the line of the deck. This will look more professional, but it’s harder to build, especially if you plan to have acrylic, Lexan, or similar material included in the top of the hatch.
Hinges for metal hatches are simple and easy to construct. They are basically one set of square tangs welded on the hatch cover to face a set of lugs welded at a 90-degree angle from the deck. A suitably sized rod, usually 3/8- to 3/4-inch (10 to 20 mm), depending on the size of the vessel and the hatch in question, is inserted through the tangs and lugs and the hatch cover will pivot on the rod. The rod will need a right-angle bend, a nut, or some similar stopper at one end, and a removable retaining device at the other end. If you install hinges on both the forward and after edges of the hatch, it will open either way. At sea, you should always have the hinges on the forward side, but in port or sheltered waters it may be useful to be able to open the hatch in more than one direction. On our current powerboat we have a hatch in the pilothouse top that can open straight up or in any one of four directions—a wonderful arrangement when one is seeking relief from the heat and needs to catch some breeze.
Any one of a variety of locking devices can be arranged to work with a metal hatch. In serious offshore cruisers, both sail and power, it’s important that the hatch can be screwed down tight to prevent pressurized seawater from forcing its way into the interior of the vessel.
The top of the inner coaming will need to be fitted with a sealing strip, as with other types of hatches. The round neoprene O-shaped material is the most long lasting and, properly installed, gives a superior seal. A proper hatch should have a separate raised coaming of sufficient height placed ahead of it and on the two sides of it, to deflect the spray and rainwater streaming across the decks and/or cabin top. Don’t underestimate the power of water and its ability to force its way into any weak areas of your deck openings.
WOODEN HATCHES
Wooden hatches are relatively easy to construct but a perfect fit will take some woodworking skills. The best way to build these hatches is to build two boxes, one being the inner coaming and the other, the hatch itself. Obviously, one box will fit neatly over the other. The inner box should be made of 2-inch (50 mm) thick hardwood, and should be 4 to 9 inches (100 to 230 mm) in height. Usually, the larger the vessel, the higher the coaming. This box will be equal in size to the inner dimensions of the hatch opening. The minimum size to allow access by the average person is 20 inches (508 mm) square; however, you should decide what size hatches are most appropriate for you and likely crew members.
It’s important the upper edge of this inner box (coaming) is perfectly square and level, as this is the edge that will contact the sealing material of the hatch itself. When you have constructed this basic square box for the inner coaming, you can cut a hole in the deck or cabin-top to match the inner dimensions of the box. Next, add reinforcing Intercostal and other beams underneath, around the perimeter of the hatchway.
Next, build the box that will be the hatch that will fit over the coaming. The hatch can be built out of 1 1/2-inch (35 mm) timber, and 3 inches (75 mm) high is about right. This hatch will fit snugly around the coaming but will have sufficient clearance to allow the completed hinged hatch to be opened and closed. So far, you have no top to your hatch. You can use 3/4-inch (20 mm) marine-grade plywood for the top, and screw and glue it to the frame. For a fancy finish you can glue and temporarily staple 1/8-inch (3 mm) mahogany or teak-faced plywood to the top of the hatch. In any case, the edges of the plywood top will need to have an outer timber strip to protect them.
You can have a Lexan or Plexiglas top instead of plywood, and you can have a combination of glazing and plywood for the top simply by fitting the ply top first, and then cutting out for the required amount of glazing. The glazed area should be of 1/2-inch Lexan or Plexiglas. When buying your glazing material, check the telephone directory and try to buy scrap material rather than specifying cut-to-size, for which you will pay a premium price.
You will need to take some special precautions when working with the plastic glazing fitted to your hatch tops and portlights. The holes you drill in the plastic must be slightly oversized. You must allow for the different expansion and contraction rate, as opposed to the timber framing. You will most likely use tinted plastic, and this will expand in hot weather; if the bolt holes or screw holes are too snug, the plastic will crack and need to be replaced. Usually, the next size up from the screw size is about right for the hole. The safest type of screw is round headed with a flat surface on the bottom of the head where it meets the plastic; self-tapping stainless steel screws are ideal. Fancy screws, such as hex-headed, sheet-metal, stainless steel screws will give you a good looking and strong fastener. Sheet-metal screws have larger threads than woodworking screws and therefore provide additional fastening surface.
The plastic should be bedded against the timber with as good a grade of silicone sealant as you can find. A small amount of the silicone sealant in each hole prior to screwing the glazing in place will ensure that the oversized holes remain watertight.
Hinges are fitted to the forward area of the outer coaming so that the hatch is aft-opening. The hinges should be heavy-duty and made of stainless steel or other non-corrosive metal. To secure the hatch from below, a number of catches and locking devices are available. One of the best is the type with screw-down devices, so you can dog the hatch down firmly onto its gaskets.
When fitting the wooden hatch, assemble it completely with gaskets and then lower it into position. The best way to make the fit between the coaming and the deck or cabin-top is to first make sure the whole assembly is set up level. Next trace the shape of the cut required, allowing the coaming to make a good fit with the deck or cabin top. Now you can bolt or screw the coaming in place through the metal deck, working from underneath the deck. Make sure you bed the coaming in a suitable sealant.
Custom hatches can be made even more suitable for the rigors of cruising with a few simple additions. You can add an extra coaming on the deck or cabin top immediately adjacent to the hatch. This coaming should surround the forward edge and sides of the hatchway. It will be slightly lower than the entire hatch assembly and fit so as not to interfere with the operation of the hatch. The extra coaming will help keep water away from the hatch. The top of this extra coaming could be timber or metal. If you make it of timber, round off the top to give it the best appearance. In all cases, the sides can have holes in their bottom edges to allow for drainage.
Another improvement to any hatch is to install eyebolts close to either side of the hatch assembly. You can use them in extreme weather conditions to lash the hatch down even more securely. The eyes need to be close to the hatch so you don’t stub your toes. Wood slats running fore and aft across the top of the hatch will strengthen Plexiglas tops and can improve the look of the hatch at the same time. These 1 by 1 inch (25 by 25 mm) timber slats can be screwed into the outer frame and then screwed to the acrylic from underneath. The slats will take some of the force and distribute the weight of persons standing on the hatch, or the weight of a heavy breaking wave. You can also make canvas covers for all of the hatches. Not only will you need these in hot climates, but they can also be a safety factor when included as part of the lashing-down arrangement
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ACCESS HATCHES
Access hatches, as opposed to hatches used only for ventilation, must be of a size sufficient to allow even a large person to enter and exit the boat in an emergency. The minimum size for an average person, as we’ve already seen, is 20 inches (508 mm) square, but don’t make hatches unnecessarily large. They must be able to withstand all that the sea can offer. You should be able to open all your hatches from both outside and inside the vessel, and you should be able to lock them to deter unauthorized intruders. Hatches in accommodation areas should be built with some form of glazing to admit light and add a spacious feeling to the interior.
COMPANIONWAY HATCHES
The main access hatchway can be in the form of a sliding hatch, a hinged hatch, or a quadrant companionway type hatch, as illustrated. Sliding hatches should not be simply a sheet of plastic running in the simplest of aluminum tracks, even though this is sometimes seen on production powerboats. Build, or buy and install, a proper seagoing hatch as your main entry and exit point.
The companionway hatch consists of two main elements: the runners, which fit on the cabin-top, and the hatch, which slides on or in the runners. The runners and the hatch may be constructed of timber or metal. If timber runners are used, you’ll need 3-inch-high by 2-inch-wide (75 by 50 mm) timber. The timber runners could be deeper, and could be bolted directly to a set of Intercostal beams situated around the perimeter of the hatchway. The runners will need to extend beyond the opening; the length is twice the hatch length plus 3 inches (75 mm). Where they extend over the cabin top, they’ll need to be screwed from inside, through to the timber.
The tops of the runners are faced with heavy (say, 1/4 by 2 inch, or 6 by 50 mm) brass strips that act as runners for the hatch top. The brass strips are set in silicone and screwed to the runners with flathead screws set flush with the surface. When it’s properly set up, the hatch must run smoothly on the brass slider.
The sliding hatch is another box, with the frame built of 1 1/2 by 2 inch (35 by 50 mm) hardwood. The corners can be half-jointed. Considerable care is needed to ensure that the frame is a true rectangle and sits perfectly flat on the runners. Around this inner frame, an outer frame is constructed from 1 1/2 by 4 inch (35 by 100 mm) hardwood. The outer frame is glued and screwed to the inner frame, with the tops of both frames flush and the outer 4-inch-deep (100 mm) frame acting as a guide to allow the inner frame to slide on the runners. The whole arrangement must slide smoothly. A hatch that jams is in no way desirable aboard any boat. Now you need an arrangement to keep the hatch on the runners, and you can do this by gluing and screwing a 1/2 by 1/2 inch (12 by 12 mm) cleat inside the outer frame 1/8 inch (3 mm) underneath the brass runner. Now the hatch has to be slid onto the runners from the front. The forward and after ends of the hatch are finished off with hardwood plates. The companionway end can have a handle or grip built into the top. The bottom of this facing board will need to be shaped to clear the cambered cabin top as it glides (we hope) forward to its fully open location.
If you have the recommended garage, then the front should be large enough to cover the aft end of this arrangement. Incidentally, the garage houses the hatch when it’s open. The garage is particularly important in forward-facing sliding hatches, as it helps to divert water away from the open companionway. It also partly provides a neat cover for the runners and the open hatch, eliminating one area where lines can snag and toes can be stubbed.
The front facing of the hatch, with the handgrip built into the top, will also need to accommodate the hasp part of your hasp-and-staple locking arrangement. The top of the hatch can be finished with 1/8-inch (3 mm) teak plywood and the whole structure coated with epoxy and light fiberglass cloth for a long life.
The top of the hatch can be three layers of 1/4-inch (6 mm) plywood, and if you’ve taken our advice and made the top match the cabin top camber, you’ll find that the plywood will laminate into a strong and durable top. A trim strip will be required for the outer edges of the plywood top to seal them from the elements.
When you’re building a timber or plywood sliding hatch above a metal cabin, the hatch opening can be finished off inside with a timber trim strip of suitable width. You’ll also need washboards (vertical hatch-boards or drop-boards) that will fit in preinstalled metal channels to complete the closure of the main-access companionway.
It’s worth noting here that any timber you attach to your steel hull or superstructure should be given at least three coats of epoxy resin, which will go a long way toward stabilizing and protecting the timber. All timber runners, hatch coamings, and the like must be set in silicone before they are either screwed or bolted in position. Space the screws or bolts at 3-inch (75 mm) intervals.
DECK PRISMS
Another form of underused light-admitting device is the deck prism. These wonderful devices admit much more light than their size would indicate, and they can be installed to be absolutely watertight and secure from the ravages of man and the sea. Check with your local hatch manufacturer and other equipment suppliers to see what they have to offer in this area. If you fit prisms, make sure your crew is well protected from contact with the sharp inside edges—but do not let this last statement put you off; deck prisms are great for admitting the most light with the minimum of hassle.
Portlights and Windows
Portlights and windows can be opening or fixed, but it’s a fact that the opening variety, no matter how well constructed and maintained, will always be a source of leaks and worry for the crew. It’s often desirable to have one or more windows or ports that can be opened; however, it’s wise to keep their number to an absolute minimum. The plans for your boat will no doubt give you some indication of the size and location of the ports and windows. Our advice is use only fixed portlights and rely on opening hatches to provide adequate ventilation.
If you’re planning to use opening ports, they should be professionally made and of the highest quality you can afford. Most commercial ports are made from marine-grade aluminum, so if your boat is built of steel or copper-nickel you’ll need to isolate the aluminum from the other metal. Neoprene is commonly used for this purpose. Don’t forget to use sleeves in the bolt holes where the ports are bolted to the hull or superstructure. Occasionally, you’ll find steel-framed professionally made ports, but they’re generally made for very large vessels so they may not be suitable for your boat.
There are many ways in which the windows can be fitted. One popular way is to set the windows back into the cabin sides or into the hull. To achieve the latter result, the window aperture is framed with an inward-facing, L-angle, shaped flange. The bottom of the L is where the window or fixed portlights will be set in sealant and bolted in place.
As you will realize, this is a more complicated procedure than simply bolting the window into a hull or cabin-side cut-out; however, the results are worth the extra effort. Set-in ports and windows give a vessel that extra touch of quality that not only enhances pride of ownership, but one day will return dividends in a better resale value. Forward-facing wheelhouse windows that will be fitted with windshield wipers will need to be glazed with toughened glass instead of the usual acrylic favoured for many other boat windows and ports.
If it’s well made, the simplest portlights or window can have an appearance that belies its low cost. The design and method of installation is simple. You cut a hole 1 to 1 1/2 inches (25 to 35 mm) smaller than the overall size of your port or window and fit and bolt a larger piece of Plexiglas or similar plastic over the aperture. The glazing is set in silicone, the holes for the bolts are drilled slightly oversized, and the corners of the hole for the portlights, and the covering Plexiglas, are all radiuses.
You can use clear silicone, but it’s preferable to use silicone that matches the colour of the area of the boat into which the port or window is being installed. If the bolts have hexagonal heads, and you line up the slots in the heads, you’ll improve the appearance of the glazed area. If the ports or windows are located in a high-traffic area, such as adjacent to the side decks, then you should have bolt heads that fit flush with the glazing and thus avoid scratching crew members who brush by the window. Be careful when making countersunk holes to allow bolts to fit flush. Acrylic can be induced to crack if it’s handled too roughly during the shaping and assembly stage.
Make sure the windows don’t have an overly large area without sufficient support in the underlying cabin or wheelhouse side. Plexiglas and similar acrylic materials come with a paper protective covering; never remove the bulk of this until the boat is completed and ready for launching. You’ll need to remove a strip of the paper, of course, after you’ve drilled for the bolts but before you install the window or portlights. The thickness of the glazing will be between 3/8 and 3/4 inch (10 and 20 mm), depending on the size and area of the aperture.
For most windows and ports, you can use Plexiglas or the harder and more scratch-resistant Lexan. You can dress up the outer edges of these bolt-on windows by using timber, stainless steel, or other suitable metal frames that can be cut to, say, 1 or 2 inches (25 to 50 mm) wide and bolted in place at the same time as the window is installed. If you use metal, it can act as an outer washer for the fastenings and will generally enhance the appearance of the windows and ports on your boat.
With powerboats, where the boat is more or less always in an upright position, and where the boat is not designed or built for extended ocean voyaging, you can be more liberal with the expanse of glazed area. Most powerboats have at least one forward-facing opening window adjacent to the inside helm position. This opening window can admit copious quantities of fresh air, and when it’s open it gives you better vision ahead in fog or poor visibility.
Even in powerboats, we find that opening windows, usually of the sliding variety, are a source of problems. Sooner, rather than later, the rubber or other material used in the bottom track for the glass will perish and allow water to enter. In some steel powerboats, it’s common practice to have the large side windows fitted without any provision for insulation. Perhaps the designers and builders feel that the expanse of glass takes up so much of the available area that it is not worth insulating the remainder. The problem is that when plywood lining is attached directly to the steel cabin side, the resulting condensation can cause problems. In one case, it was natural (though wrong) to blame a leaky window for causing discoloration of the teak plywood lining. It took some time before the culprit was diagnosed as lack of insulation in the cabin side, which caused condensation. It would have been too expensive to remedy the situation, but luckily it was discovered that a dehumidifier would solve the problem. Lesson: Always insulate all areas of your accommodation.
OUTER DOORS
As a rule, outer doors are seen in powerboats, especially trawlers. If you wish to have a door opening in the side of the accommodation, usually near the helm location, make sure it’s properly designed, fitted, and suitable for marine use. Marine doors are usually of a more robust construction than sliding windows and are therefore easier to maintain and keep watertight.
Side doors in a trawler yacht’s cabin can be built of timber and may be arranged to slide; or, if you have a very large yacht and wide side decks, then it may be possible to have the door hinged at the forward edge, or perhaps open inward. On smaller boats, a half-height, side-access door adjacent to the inside helm position may be found useful. All doors, especially sliders that are either outside or inside the accommodation, should have a means to secure them in the open position, as well as when closed.
A recent report told of a boat owner receiving severe injuries to his neck from an unsecured aluminum sliding door. Patio-style aluminum doors at the aft end of a powerboat’s main saloon? Ugh! The sliding variety, especially, are famous for lopping off fingers. And the large glass area is vulnerable to being broken in a variety of ways.
If your powerboat is of the aft-cockpit variety, then you’ll most likely have a metal aft bulkhead in which you can fit a pair of timber doors. The top one-third of the doors can be glazed, and you’ll have all the light you need. As the cockpit and after deck is usually well protected, the timber doors will need little maintenance.
On a similar subject, you may wish to lock some of the interior doors; this may slow down an intruder.
