Using smaller diameter hole/screen to the Sea Strainer ?

[BB marine]

After finding a damaged impeller at my 200hr impeller replacement. (Volvo -200 hr inspect and replace)
After talking to a Tug owner at the rendezvous (Burnt store Marina) that had his hose rerouted and a new Volvo
recommended sea strainer installed because of multiple over heating issues do to transmission cooler plugging up.
After two Years of inspecting my sea strainer and never removing any debris from it because it was always clean
After traveling the Mississippi River, opening the engine hatch to cool the engine compartment and noticing debris moving
around in the strainer. I planned to clean it when we anchored for the evening, when I did there was nothing in it.
After reading multiple post about the transmission cooler being plugged with debris and the need to inspect it. ( When I did
it was approx 50% plugged) .I never experienced any over heating.
After two years of trying to figure out how this sea strainer works with the large diameter hole screen.

I decided to find out some information about this strainer that I have never seen before. It is made by or distributed by Marine Hardware. After looking at marine Hardware catalog it appears a lot of the equipment on Tugs and Cuts come from there. The stainer is a multi port strainer with a design to break up debris small enough so that it can pass thru the raw water system. I'm sure many of you know this but I didn't. My question is, in these smaller diesel engines with relatively small tube exchangers, Trans cooler, after cooler , engine cooling exchanger how effective is this strainer? I did a search on Tugs and Cuts over heating here on this site there are a lot of post about that. I like the design of the multi port strainer. I like how it fits in the compartment and the ease of access. I don't really want to change it. I am looking to see if any one has changed the screen plate to smaller diameter holes or added a screen in addition to the stainless steel screen plate that is used. If so what mesh and was there any consequences to cooling ?

 

[dclagett]

I had similar problems all last season with overheating. We have this leafy green plant where I boat that constantly clogged either the transmission oil cooler or the external hull strainer. I found that the perforations in the internal sea strainer allow long strings of this leafy plant get to the oil cooler clogging it. The good news is that the oil cooler is easy to clean out, but I would also be interested to see if anyone has found a screen with smaller holes, installed it and has results running with it. My biggest problem though with the cooling system is the external hull strainer with slots that sucks up this leafy stuff and clogs the hull strainer. This is difficult to remove since there is no access from above and I keep my boat in the water all season (no trailer). It is also not something a diver can do easily. The only option for this problem is to haul the boat and take a wire and clean out as much as possible, but one can't get it all out with the design on this hull strainer.

Over the winter I counsulted with the yard where I keep the boat. Most inboards boats on the Chesaperke use a wedge shaped hull strainer either with slots or perforations that provides a larger raw water input area. We decided to replace the small limited access hull strainer that comes with the boat to a wedge shaped perforated hull strainer. The strainer we picked is a Groco APHS series perforated hull strainer APHS-1250-3. We chose the largest perforations at 0.188" in diameter. There are also available 0.077" & 0.125" perforated screens for this hull strainer. This strainer also has an access door so one can completely clean the strainer when the boat is in or out of the water (you may need to go swimming). In addition we changed the elbow that goes from the ball valve coming up from the thru hull to the internal sea strainer to a "T" fitting with a plug on top. From inside the boat removing the plug provides access to the hull strainer for cleanout. Also a side benefit of the "T" allows easy access for fresh water flushing and winterization of the engine raw water system.

One other item we found was that the factory hull strainer is only 1" in diameter while all the engine plumbing is 1.25" in diameter. So the new thru hull we installed during this modification is now 1.25" in diameter to be compatible with the engine plumbing.

After I get some time on the boat this season I will let report back on the results. As soon as I get an album I post pictures.