To All
After reading all the posts and taking a good hard look at my setup I have purchased a Rostan Core 75 double block, $82 on sale. Its working load is 3300 Lbs, (1500 Kg) with a breaking of 6000 lbs. Should do the job I will also be using 12mm line.
Thanks for all your help
Erik
Cat Ketch 33 #74