SHANNON 53 HPS HULL #4 CONSTRUCTION
DECK LANDING: STAGE V
(CLICK ARROWS BOTTOM RIGHT AND LEFT FOR SLIDE SHOWS)
LANDING THE DECK
#1 Here is the finished deck for Shannon 53 HPS #4 with all the openings cut out for the windows and the deck hardware like stanchions, cleats, and genoa tracks already installed. The deck is being moved into Building #1 where the Shannon crew has been working installing the systems and the interior woodwork into the hull.
#2
The deck is raised up by electric chain falls attached to the roof of the building and then lowered onto the hull.

#3
As part of landing the deck, the tops of the bulkheads that have already been installed into the hull are scribed and then cut to exactly fit to the underside of the deck. Scribing is a process where a skilled carpenter takes a drafting compass and traces with a pencil the shape of the underside of the deck unto the top of the bulkhead. When the bulkhead is cut it exactly matches the deck so the bulkhead and the deck can be fiberglass laminated together.

#4
The white formica on the bulkhead is scored and cut back so that the fiberglass tabbing that will be laminated to the

bulkhead and underside of the deck will adhere better to the luan plywood than it would to the smooth formica. The care shown in attaching bulkheads to the deck is one reason while Shannons can experience major stresses in storms and groundings with no structural damage. Production boats are regularly declared total losses by insurance companies after running aground or falling over in boat yards because of poor blocking even without major damage to the hull or deck because all the bulkheads and interior woodwork attached to these bulkheads shift from the concussion of the impact, and it would cost more money to realign the bulkheads and woodwork than the boat is worth.
#5
Here the multiple layers of fiberglass 45/45 bias biaxial laminates are coated with resin to attach the top of the bulkhead to the underside of the deck. This is a step that production boat companies skip. On production boats, the tops of the bulkheads float free and there is just trim molding that covers the gap between the top of the bulkhead and the underside of the deck. The strength of the entire structure on a Shannon is increase exponentially by attaching the bulkheads to both the hull and the underside of the deck. It does add 2 or 3 days to the deck landing process to have to carefully scribe and cut each bulkhead, and then adds another week to laminate the bulkheads to the deck. When you look at the top of a bulkhead on a production boat you cannot tell that the top is not secure. When the boat is exposed to the forces of big waves the hull starts to
to flex and the bulkheads will start to pull free from the hull because the tops of the bulkheads are not secure. Then the interior woodwork starts to move inside the hull, and doors won’t close, drawers refuse to open, etc. This is another “hidden” area on a Shannon where the extra quality (and extra dollars) go that is not apparent initially and really doesn’t start to pay for itself until the Shannon is several years old. By the time problems show on a production boat the boat is usually out of warranty coverage

#6
The deck is chemically bonded and mechanically fastened to the hull. Shannon uses Sikaflex as the sealant/adhesive to bond the deck to the hull flange. Production boat companies use 3M 5200 to glue the hull and deck together. While 5200 is a good adhesive, it gets brittle over time. Sikaflex by contrast stays flexible so as the hull flexes the hull to deck joint can move. On production boats when they get a few years old the 5200 cracks, causing leaks on the hull to deck joint. This never happens on a Shannon. Note: Sikaflex costs three times as much as 5200, so you know what product the production boat companies are going to use.

#7
The heavy duty vinyl rubrail is installed to protect the hull to deck joint. Stainless steel half oval trim is then added to the rubrail.

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