Volumetric Displacement, Q-2, I think it`s called. And blew my mind too, with the concept of a boat being built with a concrete hull !
Hydraulic concrete was sometimes even used to temporally patch WWII US Naval fighting ships from various hull battle damage until the ship could reach a dry dock repair capable port, I seem to remember reading decades ago.
Back around in the mid seventies, my at that time, live in GF`s friend`s Danish born craftsman husband, who designed and hand built a nearly 40 ft. sail boat out of concrete !
He first formed and poured a 2ft. thick slab of concrete pad to start building/forming/welding the keel with rebar, and wire mesh frame for the boat`s hull.
He then rented a concrete pumper, but I don`t remember the lime to sand density, or type concrete he selected, also I`m not sure, but I think the hull`s sides were at least several inches thick with a very smooth concrete finish both inside and out.
His sail boat`s design and hull was so well constructed, that he was able to readily get a loan from a bank after a Marine Surveyor appraised the the undecked but finished sail boat`s hull`s construction as collateral for the purchase of the sail boat`s expensive diesel marine rated motor.
The seasoned Marine Surveyor exclaimed that this home made sail boat`s concrete hull was the best designed attempt and execution that he had ever seen !
My GF`s friends intended to live on it permanently instead of renting a apartment after it was built, where they had been living since I met them several yrs. before the boat was being built. I took a bunch of color pictures of this whole impressive build with my Nikon SLR, but never bothered to scan them into any computer !
He even told me that he even had to add quite a few tons of ballast in the keel for this concrete boat to sail properly, which further blew my 23 yr. old mind !
This Danish craftsman guy was a very super detailed very high quality craftsman, and was in high demand, as a self employed master custom interior wood worker for the South FL. for wealthy mansion types down there, with everything he did, but totally lacked electrical circuit wiring knowledge (that`s where he needed me to help guide him) and he even totally hand built the outfitting of all the beautiful interior/outside wood work and even designed and hand built the sail boat`s two masts with hand selected lengths of laminated hard wood boards, while the outfitted and lived on sail boat was berthed at the Marathon Key marina !
That couple were still living on and sailing that concrete sail boat out of Marathon Key when I moved from South Miami in 1983, but I`ve lost touch after I moved, as they never had a land line # connection to the boat from it`s berth at the Marina.
