SeaHawk - Design and Construction
Page updated 6 April 2009
Hull Moulding
The SeaHawk's hull is very distinctive. Above the waterline it has the appearance of a wide planked clinker-built hull. This helps give it great rigidity. Below the waterline, the central keel has a flat bottom up to 9" wide. There are also two stubby bilge fins. Although quite slim, they do add to the stowage space beneath the two quarter berths found in the cabin.
The central keel is ballasted with concrete and scrap iron and houses the drop keel. Some reports indicate the ballast varies between 370-440lb and depended on what was available at the time of manufacture, but this may indicate a confusion arising from whether the weight of the drop keel is included or not.
Dimensions
The hull's principal dimensions are:
|
Length: Overall: Waterline: |
16' 11" 14' 6" |
5.13m 4.4m |
| Beam: | 6' 6" | 1.98m |
| Draft: |
Min: 18" Max: 36" |
0.45m 0.91m |
|
Weight: Overall (approx) of which Ballast: (approx) |
1640lb 440lb |
745kg 200kg |
Superstructure Moulding
Unlike the hull moulding, the superstructure is strengthened at various points, with boards or strips of wood moulded into the glass fibre. The entire cabin roof is reinforced with a sheet of plywood. In the left hand picture, below, the edge of the roof board can easily be made out where it meets the sides of the cabin. Other reinforcement points include the shroud anchorage and the forward part of the foredeck around the main anchor cleat.
In two areas boats have varying levels of reinforcement. The first of these is under the fore deck where the cabin begins to rise. Some boats have substantial knees glassed in while others do not. There is no obvious reason for this difference. Both two and four berth boats may or may not have them, and date of manufacture does not appear to be a factor.
The second area where differences occur is under the cockpit seating. Boats may have either one or two reinforcing strips at this point, again with no clear pattern as to why. These two illustrations are of Reedcraft built boats. Moore's boats have different bulkhead and cockpit locker arrangements.
There are no cabin linings. However, a number of optional mouldings were made. These are discussed on the Cabin Options page.
Drop Keel
An L-shaped steel plate, weighing about 70lb, swings out of a housing within the central keel doubling the draught and providing additional stability to the boat. Having a drop keel makes the SeaHawk ideal for exploring shallow tidal reaches.
Unlike many drop-keel boats that have a centre-plate housing that intrudes into the cabin, the SeaHawk's central keel, moulded into the hull, means there is space for the keel plate below the cabin floor. Only the "L-shaped" end to the keel rises and it does this under the companionway step, keeping the cabin floor clear of any intrusion.
On boats with a more rounded hull this arrangement might mean that the protruding keel under the boat, would prevent the boat from remaining upright when on a mooring that dries out. However, the main keel's flat bottom, taken together with the stubby bilge fins, allow the SeaHawk to remain reasonably upright when beached, as can be seen in the picture of Buzznack II below.
A further aspect of the keel design that makes her especially attractive to those in shallow or weedy waters. As the keel does not drop to the vertical, but only to about 30°, weeds just slide off rather than wrapping themselves around the keel. Lifting the keel is easy too! All you need to do is grab the handle in the companionway step, raise it just 18" and slip a pin through a hole in the tip of the keel to hold it in the raised position. Quick and simple, even when single handed.
More details can be found on the Keel page in this section and in the Boat Shed Section.
General Construction
The SeaHawk is not a complicated boat. There are just two principal mouldings, one for the hull and other for the complete superstructure; foredeck, cabin and cockpit. These are both built using resin, reinforced with several layers of chopped strand glass fibre matting.
The only required moulding internally is that for the cabin floor. This is bonded to the hull and incorporates support for the the quarter berths and the companionway step. This last component of the moulding is hollow and acts both as the casing for the tip of the keel and a central point that joins to the superstructure moulding, so adding further to the general rigidity of the hull.
Forward, the floor has a small opening to allow access to the keel bolt and to the lowest part of the bilges. The floor moulding only extends as far forward as the cabin bulkheads, which are considerably smaller on the four berth variant than those shown here. Ahead of this will either be the bow moulding on four-berth boats or a triangular plywood floor panel on two-berth boats. Other optional fittings are described on the Cabin Options page.
Mast Bracing
One of two methods is used to support the mast step on the cabin roof. Most two-berth variants have bracing struts rising from rather intrusive, bulkheads leading up to a wooden plate.
In the alternative version, used on all four-berth and some two-berth boats, the bulkheads maybe reduced to virtually nothing and sturdier struts, in association with a laminated wooden beam moulded into the ceiling, are used, described in a technical drawing (532kb). This approach appears to strengthen the cabin roof considerably while also providing a much more open feel to the cabin.
As can be seen, below, in the photograph of another boat, the bracing struts are embedded into the forward edge of the roof beam.
Both types of bracing are designed to take the lateral stresses on the mast step. Fore and aft stress is handled by the substantial plank of wood moulded into the upper surface of the cabin roof, on which the mast sits. The pictures of the two-berth boats show the end of the plank just protruding into the area where the roof rises to form the cabin door.
A number of owners of traditional two-berth boats have redesigned the mast bracing arrangements to given their cabins a more open feel. Some of these are reported in the Boat Shed section of the site.
Other Boats using the SeaHawk Hull
As a postscript, it may be worth noting that there are at least two other boats that have been produced using the SeaHawk hull. One was the Pedro/Señorita. Another boat with yawl rig on a SeaHawk hull has been spotted on Derwent Water in the Lake District. If you can provide information about these designs, then please use the Feedback Form.