SHANNON 53 HPS HULL #4 CONSTRUCTION
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FIBERGLASSING THE HULL
|#1- The application of the first layer of laminate set in vinylester resin for its enhanced osmotic blistering prevention (covered for 10 years under Shannon's warranty)
#2 The application of the 1" thick Corecell PVC linear foam core; the strongest and most expensive hull material available ; it can't rot like balsa does.
#3 The last layers of laminate are applied. Note the darker color where there are extra reinforcing layers applied in high stress areas
#4 The internal solid lead ballast, again very expensive but better than iron or concrete that some other boat builders use for ballast
BALLAST AND BULKHEADING
|#5 - Shannon 53 HPS hull #4 is moved from our fiberglass shop to our main building.
#6 - One of the four very heavy solid lead ballast castings being very carefully lowered into the hull.
#7- Two of the six fore and aft stringers being laminated full length into the hull. The mahogany gridwork is fastened to the stringers
#8 The ballast inside the hull
#9- The space under the gridwork is for the removeable fuel and water tanks, located down low in the hull where they belong to make the boat stiffer.
#10 -Stringers, gridwork, and luan sub sole in place.
#11- The first step in the bulkheading process - the luan bulkhead is carefully scribed to match the inner hull. Then a strip of 1/2" foam is place between the hull and bulkhead for cushioning. This step is skipped in production boats, and a hard spot forms, evidenced by a vertical line on the hull, which foreshadows eventual delamination.
#12- Next the light blue polyester half round fillet (stronger than a right angle fillet) fixes the bulkhead to the hull. Then the white fiberglass roving ropes are inserted through holes in the bulkhead on 14" centers. These ropes are laminated to the hull. These ropes create a mechanical bond between the hull and the bulkhead. On production boats, the only bond between the bulkhead and the hull is chemical, and it fails over time.
#13- The final step in the bulkheading process - multiple layers of 0/90 and 45/45 bias laminate tabbing secures the bulkhead to the hull.
Shannon 53 HPS #4 Construction Phase III: Engines and Tanks
With the basic interior bulkheads in Shannon 53 HPS #4, now we begin the installation of the engines and the tanks. The fuel and water tanks on Shannons are made by Luther’s Welding right here in Bristol, RI. Besides having a very experienced labor pool of knowledgeable boat builders, Southern New England has many vendors like Bud Luther that are the equal of the best marine suppliers anywhere in the world providing components for Shannons like tanks, rigging, and cushions.
#2 Two of the three 160 gallon (480 gallon total) 5052 mil. spec. aluminum alloy diesel tank. You cannot use stainless for diesel tanks as the sulfur in the diesel will corrode the stainless but will not harm the aluminum. A lot of builders also use fiberglass or plastic tanks but with the addition of ethanol to diesel these type of tanks can get “melted away” over time, and nothing tastes worse than water that has sat in a plastic tank for two or three weeks.
#3 Here are the tanks being installed. The water tanks slide under the cabin sole one forward and one aft. The three fuel tanks sit in between the engine stringers under removable engine room flooring. While the tanks are epoxy coated to extend their lifeuntil the year 2035 or so when they might need to be replaced. On a Shannon, it takes just a screwdriver to remove the floor to slide and lift out the tanks. On a lot of production boats, the tanks cannot be removed without taking a chainsaw to the interior woodwork or cutting out a large section of the fiberglass hull and deck. This is very costly and totally unnecessary if the builder had thought about how the tanks can come out like Walt Schulz has done here at Shannon.
#4 Here is a close-up of the dense neoprene rubber cushioning pads that hold the tanks away from the stringers. These pads are installed on the bottom and sides of the tanks to hold the tank away from the hull and stringers. While the pads are soft enough to cushion the pads, they are dense enough with a slick surface so that the cannot absorb any water. Foam is a lot cheaper and is used by production boat builders to cushion tanks, and not surprising the tanks always corrode where they are touching the wet foam pads.
#5 One of the two Yanmar 4JH4 110HP diesels to be installed in Shannon 53 HPS #4. While engine selection is owner choice, Yanmars have a history of rugged durability and a world-wide service network.
#6 Here is one of the Yanmars sitting on temporary blocking on the engine stringers. The big installation stress on a diesel engine comes from the torque of the engine. The engine as it turns is trying to twist itself off the engine beds. On most boats, the engines are just screwed into the wood or fiberglass stringers. Over time, the forces from the torque of the diesels compromises these screw holes, and the engines vibrate like crazy. Again, this is another instance of “fast and dirty” production boat manufacturing methods that saves the builder a little bit of money but then costs the owner 5 or 10 years in the future a lot of money. To make sure that the motor mounts never come loose from the engine beds on a Shannon, when we are laminating these engine beds we encapsulate a 1” thick solid aluminum plate under many layers of fiberglass. The plate is then tapped to receive the eight hefty machine lag screws that hold the engine in place. This is just another example of the “hidden” quality found on every Shannon that really doesn’t become apparent until the boat is several years old.
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