Raw water scoop needs cleaning

Hi all, in the photo below, you can see there is quite a bit of barnacle growth in the main raw water scoop for my 2012 R27. Other than blindly poking and pulling and scratching and cursing with some dental picks, I was wondering:

1. Can this scoop be removed easily without any major work to the thru-hull? and then really be cleaned up?

2. Other ideas for cleaning with the scoop in place?

Pic: https://photos.app.goo.gl/nqK3KwWArw89Yf84A

Thanks,

GF

Do yourself a favor. Remove it and install the correct size 1 1/4" thru hull. If not just pick away at what you can get. Increasing the size of the thru hull is on my to do list. Now that I'm going to cruise in warmer water it is a must.

Check out my photo album for the fix I did to solve this problem and others.

These before/after photos show my modification that has worked well for five years on the Bay:
https://photos.app.goo.gl/3aEKxXs6TjN18WnN8
The next step for me would be the interior part of dclagett's mods which was just an idea a few years ago, the thought being to replace the 90-degree elbow on the seacock with a tee that has a plug at the upper end and the hose/nipple on the side outlet. As needed, remove the plug, open the seacock, and use an appropriately sized dowel or broomstick to ream/tamp out the thru-hull.

I like that idea with the "T" for a cleanout. It's on my list now.

When I hauled out this fall I took a good look at my inlets. Not as bad as CaptCrunch's but not pretty. I scratched and picked that areas I could access, but it still worries me. I've been thinking of a plan for next spring.

How about some duct tape on the outer surface to make it (sort of) water tight. Then pouring some Barnacle Buster into the sea strainer and letting it sit for a couple hours. Then remove the tape and rinse.

Comments? Has anyone else tried this?

I should hasten to add that I haven't tried the reamer tee yet. I think I must have seen that setup many years ago on somebody else's boat, which almost certainly means it was an auxiliary sailboat, not a motorboat, which probably means it was a flush or a mushroom thru hull, not a scoop. I have some doubts about how effective a reamer/plunger would be with the scoop limiting its stroke. Also, I should note that the main benefit from removing most of the screen on the scoop - as in my photos - is that it's easier to get bottom paint onto the areas of the hull and fitting where the little buggers usually thrive. I do know that D3 overheating hasn't been a problem since I took the dremel to the scoop, and GADGET is usually in the water 363/365.

Capt Crunch... You have a Volvo? I thought you had a Yanmar like me.

It'd be nice to have access to, and through, the ball valve. A short standpipe on the top of the tee should be all that is needed. Anyone have an idea how tall it needs to be to get above the waterline?

dclagett":3uazlw2o said:

Check out my photo album for the fix I did to solve this problem and others.

Click to expand...

dclagett, what exactly is involved in removing the scoop? I only saw 2 holes for a fastener (screws?). Did you just remove two screws and pull the scoop out of the thru-hull fitting? Thanks, GF

rpmerrill, I actually thought the same thing about Barnacle Buster but thought maybe it was too hokey a solution. Seems like an easy enough task to do. Duck tape the inlet. Open the the main sea strainer and pour in BB and let it sit. I would feel better doing that AND removing the inlet screen to clean and prepare with bottom paint tho.

GaylesFaerie,

I did not remove the clam shell myself however in looking at it after it was removed I think it was sawed off. The clam shell that was on my boat included a thru hull as one piece. Not sure why it was sawed off, maybe they were having trouble removing it.

Finally got around to doing an internet search on "seacock water strainer" images. Yup it is one piece and not a trivial job to remove. Once removed, I would replace it. I'm gonna give the Duck Tape and Barnacle Buster a try and will let you know how it turns out. Thanks all, GF

Just noticed them this haulout! Thanks for the 'heads up' guys.
On R27 O/Bs, there are 2 raw water scoops. One on either side of the far-aft keel.
Mine weren't badly fouled (thanks to some overpaint with the anti-fouling stuff).
Picked mine clean'ish' -then sprayed with Prop-Coat's 'Barnacle Barrier' (like for props, trim tabs). Doesn't seem to work that well on white-worms (which is mostly what I saw on these intakes).
We'll see how it works in Chesapeake Bay waters in '21.

I have found that cleanest raw water sea water pick up screen that is installed is marginal at best. This subject has been discussed in many threads on TugNuts. If this question is asked to any 180 hp Yanmar powered Tug or Cut owner or any Volvo D3 200Hp or 220 hp owner ( If you run your engine at WOT for 10 minutes what is the engine temperature running at?) I would guess the answer would be 20 F degrees above normal operating temperature of 180 F +/- 2F. (198 F to 202 F) I would guess that many will say "I can not run my engine 10 minutes without it over heating"

In a thread posted earlier this year a new owner of a lightly used C26 was having high rpm over heat issues. This owner was told by the servicing technician that after referring to the VOLVO manual
" As per Volvo manual that motor requires a 1 ¼” seacock, and it only has a 1” and there should never be a hard 90deg fitting on a motor inlet, only a swept 90. Couple that with the extra items pulling off that strainer and it’s a recipe for high temp".

Photo of what the technician is talking about. This is the install that I have been looking at in my C26.
gallery2.php?g2_itemId=68961&g2_imageViewsIndex=1

This statement is correct. The Volvo minimum requirement is 1 1/4" for D3. D3 specification for nominal raw water flow at WOT is 4.9 cu ft per minute @ Nominal raw water pump design head pressure is 18.9 psi.which would be 36.65 GPM. A 1" pipe has the capacity of 26GPM @ 20psi This calculation would be for straight pipe no elbows. Add a couple 90 degrees elbows into the equation and what you have when the installation is new is an install that works marginally.


1" straight pipe @ 20psi max flow =26 gpm - Volvo flow requirement @ WOT 36.65 gpm max pump capacity is 18.9psi

The Raw water scoop installed R25, R27, C26 scoop dimensions is 4" long and 2.5" wide Marine hardware part# HSWP1.000-B

The minimum requirement specified in the Volvo manual 1 1/4". Below are flow and size of 1 1/4" if installed.
1 1/4" straight pipe @ 20psi max flow = 47 gpm
The 1 1/4 Raw water scoop made by Marine hardware scoop dimension 6.5 " long and 4" wide . ( considerably larger )


In a thread regarding this subject. Andrew said " I have never heard of this issue coming from our waters. I know that they did not overheat early on so potentially an issue down the line that has restricted water flow through the original seacock.

I believe he is correct in this statement in many ways. "our waters" I'm assuming he is talking about the waters in the PNW. I looked at a chart posted by NOAA. The average temperatures posted for July/August in Pacific coast north were mid to upper 50's.The new C26 owner of the lightly used boat operated their boat in Northern Massachusetts with slightly higher temperatures than PNW but not that much different. What happens if you boat in Pensacola FL ? Average temperatures in July/August 86F. There is a wide range of water temperatures based on where we boat. Engine manufactures take this into consideration when they design marine engines. The requirements are based on worse case. They always use a service factor variable in their specifications. " I know that they did not overheat early on so potentially an issue down the line that has restricted water flow through the original seacock".
Probably true, Boats are designed to be used for years. Over the years no manner how well you take care of your engine there will be some corrosion build up, some marine growth, erosion of material that helps dissipate heat....No matter how much cleaning and maintenance you do there will be some restriction. A system installed as per manufactures specs should still operate correctly because it has the service factor built-in. This service factor is in the design of the engine and the requirements of the installation. A marginal system install will be exactly that, marginal, and higher operating temperatures could be the result.

When I looked at GaylesFaerie' and CaptainCrunch's photos I see the same undersized raw water scoop that I have. If 25% of it is blocked the already marginal 26 gpm capacity is now down to less than 20gpm close to 40% less than required. That is an equation for an inadequate cooling system. If the recommended 1 1/4" raw water plumbing was installed and there is 25% blockage the system would be operating close to the the nominal raw water flow requirements @WOT.

My C26 used on Lake Michigan operated at WOT for 10 minutes would reach 192F When it was new and when it had 430 hrs on it. Lake Michigan water temperature in July/August Average is upper 60's to low 70's. Lake Michigan being clean fresh water does not cause much corrosion or marine growth. The boat is in the water no more than 4 months a year. When running the boat down the rivers of Tennessee , Mississippi and Alabama this fall and then in the northern waters of the Gulf of Mexico after 5 minutes of WOT I would see 201F, ( much higher water temperatures) I I backed down to 3600rpm and still saw 190F engine temperatures. Water sea water temperatures were upper 70's.

The point of this long drawn out explanation is when you start having overheat issues because of obstructed ,corroded, fouled raw water system. Or find the system is getting fouled and you want to repair and clean it. Using bandaids will help but it will not correct the issue. The installed plumbing will work in cooler waters, when all plumbing is cleaned, flushed, and no obstructions. Or operated at 50% or lower load. When I get to the point that I need to clean or repair the plumbing it will be upgraded to what the Volvo recommendations are. 1 1/4" plumbing with a larger raw water pick up scoop and a larger sea strainer.

I have spent some time looking into this upgrade. I don't like throwing the throttle down and watching the temperature come up. The upgrade is a lot of work so to do it I need to convince myself that it would be worth while. The a common reason for diesel engine longevity loss, is over heating. I guess that is a good reason.

Water temperature averages.
https://www.ncei.noaa.gov/access/data/c ... meanT.html

Am I right that even with a pristine 1-1/4-inch seacock and thru-hull, my D3 200 would still be undercooled per Volvo since its water supply is limited by the 1-inch outlet nipple on the multiport strainer? BTW, what size is the inlet on the D3 raw water pump?

CAPTCRUNCH":283tdp7z said:

Am I right that even with a pristine 1-1/4-inch seacock and thru-hull, my D3 200 would still be undercooled per Volvo since its water supply is limited by the 1-inch outlet nipple on the multiport strainer? BTW, what size is the inlet on the D3 raw water pump?

Click to expand...

Your are right, If your are going to replace the original install it would require 1 1/4 " seacock, the multipart strainer has a 1 1/4 " inlet port but it is plumbed with a 1 " NPT barb fitting the outlet discharge port is unfortunately 1" this would require replacement, to do it right. The reverse gear cooler is 1 1/4 " and the raw water sea pump has 1 1/4" inlet and outlet ports. The installation rule of thumb( Marine industry) for seacock and strainer sizing minimum is pump inlet/outlet size. (acceptable). Many times the boat manufacture chooses one size larger. I have always thought that 1 1/2" was the standard size for a seacock. (boats in the 30' range). I was surprised when I saw the small 1" being used on the C26 with 220hp.

Not to change the direction that this thread is heading but I made a modification to clean my seawater strainer that others might find helpfully. What I did was install a fresh water wash down in the cockpit area, next I installed a ball valve in the seawater line between the hose connection for winterizing and the water pump. To flush the sea water scoop, I shut the valve fwd of sea water pump (this will ensure engine not getting hydro locked) hook up hose from cockpit to hose connection on seawater system, pressuring system and open hull valve. This is great for clearing sea weeds and other debris, I did this to being able to do a soft grounding and clear the intake prior to starting engine . Bob

I'm supposed to be helping bake Christmas cookies, but I'm distracted by the puzzle of how best to move BTUs (air and water) in and out of the engine space of my R27. Also, I'd rather face the possible peer review here than in the kitchen. I'm wondering if somebody here can "imagineer" a raw water system that uses hoses and fittings to create the functional equivalent of a manifold that ties together the boat's 3 existing thruhulls and the 5 consumers so as to supply the specified volume of raw water to the engine as highest priority and then to the others as desired/available (?not simultaneously?). Where's Rube Goldberg when I need him? See https://www.youtube.com/watch?v=RBOqfLVCDv8 for inspiration (long winter nights, I guess). Cookies are done. Have a Merry Christmas, all.

It's not easy at all to take it out. Mine also had a 90-degree turn in it as well using an elbow that wasn't really for that purpose. I cut off the scoop part, and replaced the elbow with a bronze, straight through fitting. My research and speaking with liveaboards who travel extensively was that the scoops tend to get fouled and you need to go into the water to clean them. They remove the scoops and put in a straight-through marine-grade fitting.

So I did it and when something blocks the inlet (which actually occurs less often with a straight-through fitting) you just close the valve, remove the hose, put a properly sized wooden dowel into the through-hull, open the valve and push out anything blocking the inlet. You don't get wet and the blockage is cleared in a few minutes.

Here is an excellent site that covers through-hulls quite nicely: https://pbase.com/mainecruising/boat_projects