Our Islander 28 has a fw heat exchanger. This allows some time before I need to open the rw thru hull after starting as all A-4 operators should do. That is a good thing! Getting to the valve to open the rw intake is not fun. All thru hulls get closed before leaving the boat so this is an exercise that is part of any day aboard. This year I replaced the rw thru hull valve and positioned it to allow a cable with a clevis end to push it open and pull it closed. Wonderful! Now, upon starting, I can just push on a "T" handle mounted just inside the cockpit's port hatch, rw starts to flow and the wl muffler starts doing its job. To shut this down I pull the "T" back up to seat the valve closed. The throw of the cable control opens the thru hull valve about 90% when fully down. It closes it solidly when pulled up. The water flow is adequate since the large strainer we have churns and is always full. The volume of water coming out of the exhaust is normal. I am enjoying being able to control this from the cockpit now.