petter raw water cooling

[martinwill]

Hi, my petter PH2W inboard engine is raw water cooled with sea water, does anyone know where or if there are sacraficial anodes on it ?, I cant find any. Would it be possible to fit them any how would i go about it.

[rbodell]

Everything should be bonded anyhow, the shaft, strut, ruder, and especially through hull fittings etc. You should have zinks on the shaft and rudder anyhow and better yet some more fastened anyplace you can put them. Connect a ground strip, preferably copper to everything including the engine. If you have a steel hull you should weld some wherever you can on the hull. usualy every 8 to 10 feet is good, If you have a sailboat don't forget the chainplates, mast etc. Anyplace you can get an addiyional zink below the water line is good. NOTE, when you are at the bock, that is when most electrolysis occure4s because nearby boats with electrical problems as well as dissimilar metals cause excessive electrolysys. You can take A piece of battery cable and put a zink on the end of tio and a battery clam,p o0n the other end. While at the dock clamp the battery clip on to anything else that is bonded to the rest of the boat.

Look for a pipe plug in the water lines in the block. If you can't find one, you can put a piece of pipe in the water line with a T in it. Reduce the third side of the T down to the thread of the zink and install it in the cooling water line. Run a ground from the pipe to the engine. NOTE, be carefull about adding a heavy unsuported pipe to the engine block. Viberation can cause it to break and sink your boat.

[dkwflight]

Hi  No indication where you are from.,

I found several different size zinc anodes at McMaster-Carr here in the states,

I also heard them called zinc pencils. You can find them with pipe plugs on one end.

I do know you should inspect the coolant passages for mineral  build up at least annually. Do an acid wash if there is any build up at all. I have seen raw water cooled gas engines packed solid with barnecles etc. Ruined as a result.

As with all engines, don't over cool them. They need to run hot.
Dennis

[rbodell]

Hi  No indication where you are from.,

Florida origionaly. Spent most of my life in the fishing industry and 20 years sailing single handed without an engine around South America and the Atlantic. Now I live near Ft Worth Texas as far from the ocean as I can get.

I found several different size zinc anodes at McMaster-Carr here in the states,

I also heard them called zinc pencils. You can find them with pipe plugs on one end.

Yep those will do it

I do know you should inspect the coolant passages for mineral  build up at least annually. Do an acid wash if there is any build up at all. I have seen raw water cooled gas engines packed solid with barnecles etc. Ruined as a result.

As with all engines, don't over cool them. They need to run hot.

A salt water cooled engine should run a little cooler than a fresh water cooled engine. It keeps mineral deposits down. salt watyer cooling is definately not good for any engine. It would be a real good idea to incorporate a heat exchanger into the cooling system especialy since you have an engine that will probably outlive you. Listers cool easily, so you could probably even buils one that would work.

Good luck, keep the red side down.

Dennis

[dkwflight]

Hi What about a keel cooler or a plate cooler built into the hull?

I would think coating the coolant passages with something would help corrosion.

Dennis

[rbodell]

Hi What about a keel cooler or a plate cooler built into the hull?

Well, now that you mention it, I built a keel cooler for a guy that did some illegal dredging (propwashing) bercause of all the sand stirred up in the water. It was very simple and no through hull fittings. Basically there was the day tank to keep it full. Copper tubing went from trhe water pump through the transome above the water line. down and under the boat forward along the keel. Up near the bow it made a 180 and back. Then up and back through the transome to the engine and water pump. There was also a bypass with a thermostat in there.

I would think coating the coolant passages with something would help corrosion.

Bad carma. it also affects the transfer of heat. If you use copper bottom paint, you get dissimilar metals that increase the electrolysis. That is why the boat yard never paints the shaft and prop. They do have some NON-Copper based antifouling like they use on outboard motor lower units, but you still affect the transfer of heat.

Dennis

[martinwill]

Finally found where the anodes are (thanks to Doug), they are zinc tubes mounted on brass plates in between the water inlet manifold and the block.
Mine were totally gone so i machined some out of zinc rod and soldered them to the origional brass plates.

[haganes]

i missed the original post.

in my experience a raw water cooled engine does not have a long lifespan (even with all the zincs you can cram into it).  you will see a further reduced lifespan if you haul you boat for the season.

i would recommend a heat exchanger or keel cooling to protect all the good looking work you have been doing.

regards,
captain steven

[martinwill]

Can anyone tell me what a keel cooler involves, is it a tube that runs along the keel or a flat coil type arrangement sitting on the underside of the hull, can they be homemade, such as copper tube, what length of tube and diameter are there any formulas for working them out.

[Bluecometk]

  Martinwill, there are a few different types of keel coolers. The first is a series of pipes that runs the length of the keel in series front to rear. Next is a series of pipes running the length of the keel that are connected to a main feed pipe and branch out in parallel like the tubes in a car radiator. They both carry an anticorrosive coolant to and from the block and heads and sometimes the oil and trans coolers. They both will require a circulator pump and a raw water feed pump. The raw water feed pump will still carry water to the manifolds and risers if equipped. The circulator pump will move the coolant to and from the block and heads. You will also need an expansion tank and overflow tank. The downfalls of the keel cooler are, it can be damaged by collisions with bars, reefs, the bottom, debris and corrosion. It also has another enemy, barnacle type growth that can diminish its cooling capacity. If the boat is run regularly, this is rarely a problem. The benefits far outweigh the pitfalls. The shape of the pipe is usually round and of an anticorrosive material. If you are working with a solid keel the feed and return pipes can be put through the garboard plank or area next to the keel. Keel coolers are normally used in slow moving boats (displacement hulls) not planing hulls because of the drag associated with the external piping.

There is one other type cooler but it really doesn't apply to you unless you are very ambitious or building a big Tug, its called a courting nozzle. This type is a circular shroud that goes around the prop with a hollow center to house the engine coolant. The nozzle in some cases turns in series with the rudders to vector the prop wash where it is needed most.
I hope this info helps.
Bluecometk.

[martinwill]

Thanks for that, i would also have to run a dry exhaust or have a seperate pump to raw water cool the wet exhaust, the same if i was to fit an on board heat exchanger. so many different ways of doing things. not sure which way to run, the easiest being leave it raw water cooled !!

[Bluecometk]

  Martinwill, I would go raw water cooled in fresh water bodies and wet exhaust, its more comfortable on the ears. If there are any dips or crowns in the exhaust piping as the water builds and flows it will give your engine its own unique sound.

  I'm not familiar with the petter block integrity but I think that most engines would last in fresh water quite a long time if raw water cooled. For example my fathers boat had two Hercules block (Chris Craft conversions) in it. They were 1948 200HP, 404ci 6 cylinders. He bought them new and they were run in the Chesapeake Bay/Delaware River area until 1988. In that time the only problem ever incurred was in 1981 on one engine, the exhaust manifold rotted through leaking water into the cylinders and causing a misfire. To put it in perspective The engines were so worn-out that for every 35 gallons of fuel burned they would burn a gallon of Fox 50w oil. But they started every time and ran without a problem so they stayed in the boat until it wore out.(1934 Wheeler custom sedan 40').My dad had an another boat a1950 Matthews 42' he put Chrysler 440s in it in 1970 and they ran until his death in 2004 and they also were raw water cooled. The only problems with them were that the exhaust manifolds would rot out or clog up about every 10 years.

What I'm saying is what ever the route you go don't worry about it just have fun.