Originally Posted by pstorti

Two are for turbo boost, measured in the intake manifold after the intercooler, two are for sea water pressure in the open side of the cooling system, and one for diesel fuel pressure leave the filtration system. The water pressure sensors might make sense to have snubbers to prevent damage from spikes when the boat renters the water after getting air. All can be 1/8" NPT thread, 0-50 psi output, 10' of cable should be plenty, and have to be 4-20 ma output.