auto cooling sys run at what 16psi or so are jets run wayyyy more than that. i know i know every joe shmoe runs heater hose for the last 30 years and has had no problems.... well im not joe shmoe and not even close to that lucky... so do yourself a favor and at least get the 300psi hose and push lock a/n fittings and never worry about blowing a hose and sinking your boat with your family....
just my .02
And Ralph has a valid point. Personally, I've run both braided and regular heater hose. My preference is to run the Blue Goodyear stuff (I've used up my supply of "Rainbow Brite" band-aids messing with braided SS...... THAT stuff is brutal to work with......and totally unnecessary save for the "Bling" value....), but I've also run regular NAPA 5/8" hose, hose clamps, with zero problems, save for one incident at Lake Mead where a hose blew off because some idiot (ME, although I still blame RJ for that just for convenience....) forgot to tighten ONE hose clamp..... Then again, I've always run a valve at the jet to control water to the engine.
Where pressure from the jet tap used to be a non-issue (Within, say 15-20 PSI, where the old boats of the 70's ran forever as they were) I think that has changed with current equipment, parts available and tolerances. It can be hidden just in changing the impeller and wear ring to a modern one in a pump yourself and the pressure from that tap that goes to the engine can double.
THAT being said, the hoses are not the weak link. Rarely do you see those things fail, even standard cheapo 5/8" heater hose from Pep Boys. What fails are usually head gaskets and intake gaskets that cause the "Milkshake" from this.
Not to counter Ralph, or anyone else, but standard heater hose can take any reasonable pressure your pump can deliver out of that engine tap. The hose will NOT be the problem in an over pressure situation. It'll be something more serious.
Ray
