If you weren't wedded to 3/4 I would use these, but they are 5/8.. http://www.jamestowndistributors.com/userportal/show_product.do?pid=57106&familyName=Moeller+Elbow+Thru-Hull+Vent Jim Davis S/V Isa Lei "Coffee tastes better if the latrines are dug downstream from the encampment." US Army Field Regulations - 1861