I used 4 inch sch 40 pipe for the mooring bits on Silas Crosby, ran thru a 12 inch square , 3/16th doubler plate, to a point ten inches below decks , where I welded it on a horizontal piece of plate, which was welded to the transom. You can see this bit in the bottom of the picture, next to the chock
. It has a sheer strength of 90 tons.
If there was a chafe problem , one could run a short length of chain around the bit, to take it clear of the hull, where the rope would be attached.
The Silas Crosby has a single aluminium door for a main hatch
, which is extremely tough and resistant to any boarding wave. She is also a centre cockpit boat, which makes her even more resistant to boarding waves.
Altho I have never cruised in a boat with a reverse transom, those who have, said they invite, and even launch a breaking wave into the cockpit. The difference between a reverse and traditionally sloped transom is around 6,000 lbs of extra buoyancy in the stern of the boat with the traditional transom. Thus, a reverse transom may be the cause of waves ending up in the cockpit.
Being a steel hull, she has a fraction the structural worries of non metal boats.
She has since rounded the horn
On a fibreglass boat a large stainless U bolt in the corners of the transom, with huge backup plates would be the best attachment points for a drogue.
With the drogue shackled on, thru hard eyes, there would be zero chafe.
I built my own parabolic drogue from salvaged seat belts ( free) , using a large mooring ball , about 5 ft in diameter , as a mold. I stapled the webbing in the shape of a half sphere over this ball, then sewed it later, while removing the staples.
A friend on a Fraser 41 , during the queens birthday storm off New Zealand used this type of Galerider drogue with good success. He kept having to shorten the rode
to stop it from fouling the skeg, in the troughs, when the line
went slack. When it was down to 80 feet , it worked far better, the rode
stopped going slack, and they went to sleep til the storm was over. This saves one from having to carry a huge amount of line
Boats with drogues from the bow tend to lie beam on, which is far less comfortable and puts far greater loads on the drogue and line