Originally Posted by imkashmo
I'm installing a mooring system in Kaneohe Bay on Oahu, Hawaii. Its 40 Feet deep, mud/sand bottom. Windward side. Having to submit a diagram, just wanted to see if anybody had experience doing this? Its a 45 Foot Trimaran, 20 Foot Beam (18 ton displacement -according to my research). Mainly need to source the materials. There are already 54 personally installed moorings at the site but nobody has bothered to put up a blog or info.
That's a big boat to keep off the beach. If it were me, I would put on the mask and snorkel and take a look at what the others in the bay are doing. Although the moorings I've used have been concrete blocks, they've been for smaller boats in a more protected area.
If I were in your spot, I think I would check locally to see if anyone is installing the helix mooring rods. If they were not available, I would start checking to see if I could get a hold of some used railroad wheels to string together two or three with some B.F. chain tying them together and then some smaller chain coming off the bottom with an underwater float holding it off the bottom and then some 1 inch nylon rope up to my mooring ball. There are some folks advocating the use of large mushroom anchors here as well that appear to hold very well once they are buried. A check of the moorings around you may give you an idea whether a mushroom anchor would work for you.