20170501

Hull Variation H4B

Changes from H4A:

• Added 2cm freeboard
• Added bulkhead at S500 to split bow tank into 2 compartments.
• Added bulkhead at S4100 to split stern tank into 2 compartments.

Hatches

Considered elliptical vertical hatches in the mast bulkhead and aft bulkhead, but rejected these because the hatches would be rather small and hard to reach. Considered wooden deck hatches but rejected this because they would not lie flush with the deck. Decided to use standard 370x370mm Talamex deck hatches from Lankhorst-Taselaar for the bow and stern tank. These hatches have a low profile, are strong and inexpensive.

Having decided to use deck hatches I decided to add extra bulkheads to create airtight compartments in the ends. The airtight compartments may be vented with inspection hatches which should be closed when sailing on open water.

Decided not to use the daggerboard box for extra buoyancy. We already have 476kg of which 185kg are in the bow, 225kg in the stern and 50kg in the hull skin.