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Author Topic: raw water strainer removal  (Read 930 times)

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mdidomenico

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raw water strainer removal
« on: February 10, 2018, 05:48:38 PM »

I started to pull the thru-hulls in anticipation that it's getting warmer and i'll be able to replace them all with proper groco seacocks.  four of the thru-hulls came out surprisingly easy.

however, i can't seem to get the raw water strainer off.  there are four screws at the corners that poke through the hull and into the head compartment.  I've removed the nuts and tried banging on them with a hammer.  the didn't even budge backwards a nanometer.  i then tried hammering a wide flat putty knife between the hull and the strainer.  sadly no joy

am i doing something fundamentally wrong or did i miss a step in removing the strainer?  i don't plan to put it back, so i'm not above damaging it, but i don't want to if i don't have to and i don't want to damage the hull.  so even though i was hammering on it, i stopped short of "hey this might break something" level of force.

the pictures are from the survey, I've already removed the hoses and marelon seacocks...

on a separate but related note, I'm a little perplexed by the sizes of the thru-hulls.  it looks like to me the macerator, head/kitchen sink drains are 3/4", the toilet intake and raw water intake are 1/2".  since groco doesn't make a 1/2" assembly, is there any issue with enlarging all the holes to 3/4" or should i go larger on any of them?
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Ron Hill

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Re: raw water strainer removal
« Reply #1 on: February 11, 2018, 02:40:28 PM »

Md : Looks to me like you are going to have to chisel off that outside strainer that a PO put on.  I'll guess that it might even be caulked on the seams? 
Have you tried taking a wooden dowel and hitting it from the inside to drive it off?

A thought
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mdidomenico

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Re: raw water strainer removal
« Reply #2 on: February 11, 2018, 04:01:54 PM »

I'll guess that it might even be caulked on the seams? 
Have you tried taking a wooden dowel and hitting it from the inside to drive it off?

i didn't see any adhesive, but i wouldn't shocked if there isn't 5200 under it somewhere.  i had thought about the dowel.  unfortunately i didn't have one and i figured before i went to town on it i'd see if i was doing something stupid.  i'll give it a whirl next weekend.
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Jon W

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Re: raw water strainer removal
« Reply #3 on: February 11, 2018, 05:03:48 PM »

For what itís worth you appear to have ball valves threaded onto the thru hulls, not seacocks. A traditional seacock is a 90 degree rotation ball valve with an integrated flange that attaches it to the hull (or backing plate) and the thru hull threads into it.
« Last Edit: February 12, 2018, 07:59:51 AM by Jon W »
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Jon W.
s/v Della Jean
Hull #493, 1987 MK 1, M25XP, Manson Supreme 35
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britinusa

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Re: raw water strainer removal
« Reply #4 on: February 12, 2018, 01:45:35 AM »

Although it's unlikely that anyone could apply excessive pressure onto the hoses on those thru hulls below the bathroom cabinet, it's still a good idea to do it right.

http://www.pbase.com/mainecruising/backing_blocks

Paul
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Paul & Peggy
1987 C34 Tall Rig Fin Keel - Hull # 463

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mdidomenico

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Re: raw water strainer removal
« Reply #5 on: February 12, 2018, 02:27:20 PM »

For what itís worth you appear to have ball valves threaded onto the thru hulls, not seacocks. A traditional seacock is a 90 degree rotation ball valve with an integrated flange that attaches it to the hull (or backing plate) and the thru hull threads into it.

Yup, that's only the tip of the iceberg of scary stuff i've found as i tear through this (new to me) boat.  all the thru-hulls are getting replaced with proper groco sea cocks.  the picture was merely to show the bolts.  all the marelon and dry rotted hoses are already gone...
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Ron Hill

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Re: raw water strainer removal
« Reply #6 on: February 12, 2018, 03:01:59 PM »

Md :You'll have to remove the hose in the picture and then unscrew the all valve so you can then use a 3/8" wooden dowel and try to drive off that strainer. 
If everything comes off down to the thru hull itself you might be able to use a 1/2" dowel.

A thought
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Jon W

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Re: raw water strainer removal
« Reply #7 on: February 12, 2018, 05:27:25 PM »

Marelon flanged seacocks are a good product. One of the first things I did was remove all the ball valves and thru hulls then replaced them with Marelon flanged seacocks mounted to backing plates. Flanged bronze seacocks are also a good product, but require bonding and also run the rare risk of blowing out of the hull if the boat is struck by lightning.
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Jon W.
s/v Della Jean
Hull #493, 1987 MK 1, M25XP, Manson Supreme 35
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Fred Koehlmann

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Re: raw water strainer removal
« Reply #8 on: February 13, 2018, 11:43:57 AM »

I second Jon's interest in Marelon. I know bronze has historical precedence and is the proven metal, but I'm all into reducing as much metal below the waterline as possible. This might be a personal bias since as a teen I remember being hit by lightning, and in that case what saved us was the large twin bronze grounding plates that all the standing rigging was attached to. After that, I research all about lighting, grounding and bonding. The less metal below means less maintenance of a bonding system. IMO, perhaps others think differently.
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mdidomenico

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Re: raw water strainer removal
« Reply #9 on: February 13, 2018, 06:47:36 PM »

I certainly don't have enough knowledge to be for or against marelon for any technical material reason.  I read way too much on the internet and have heard the good and the bad of both marelon and bronze.  so here's how I personally made the decision, this is just my opinion:

1. cost was close, assuming one piece with flange and valve (the split flange/valve is slightly more expensive)
2. i like that the bronze comes in a flange and a separate valve, means not having to disturb the thru hull if a valve freezes up
3. i like that groco sells backing blocks, i could order a sheet of G10, but once i did, bought tools, and cut circles, it was roughly the same cost
4. bronze has a slightly longer history, small advantage, but newer isn't always better
5. mainesail endorsed! :)

the last and biggest came down to, I just don't like the way the marelon feels.  to me, even though i totally know it isn't, it feels like cheap chinese junk you'd get at walmart.  i know that's a totally unfounded irrational feeling, but it would keep me up at night worrying about whether my boat is sinking...

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Noah

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Re: raw water strainer removal
« Reply #10 on: February 13, 2018, 08:16:07 PM »

Staying out of the bronze vs. Marelon fray, but have a question: are you going with flush or mushroom thru-hulls? If flush, how do you plan to match/deal with the bevel in the hull? New thru-hulls/seacocks are on my list for my next haul out in May.
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Jon W

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Re: raw water strainer removal
« Reply #11 on: February 13, 2018, 08:54:47 PM »

There are copy products out there that imply they are Marelon, but they arenít. If itís Marelon it says it on the part. Much of the Marelon poor test results is with a ball valve threaded onto a thru hull, not a Marelon flanged seacock attached to a backing plate. End of the day youíre right, itís what you are comfortable with. Remember bronze contains zinc. Stray current and salt water should drive a good bonding/earthing design.
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Jon W.
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britinusa

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Re: raw water strainer removal
« Reply #12 on: February 14, 2018, 05:04:42 AM »

Staying out of the bronze vs. Marelon fray, but have a question: are you going with flush or mushroom thru-hulls? If flush, how do you plan to match/deal with the bevel in the hull? New thru-hulls/seacocks are on my list for my next haul out in May.

I have recently added a thru-hull, in the v-berth, for the Air Conditioning Raw Water intake. I purchased a mushroom thru hull, but screwed up and had to go to WM to get a replacement, they only had the flush mount.

To match the bevel, I used a 1/2" belt sander very judiciously, it took me about an hour to cut the bevel in the hull (solid, not cored).

I have to think that someone has come up with a suitably angled countersink to do the job in a few seconds.

Paul
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Paul & Peggy
1987 C34 Tall Rig Fin Keel - Hull # 463

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mdidomenico

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Re: raw water strainer removal
« Reply #13 on: February 14, 2018, 07:53:12 AM »

Staying out of the bronze vs. Marelon fray, but have a question: are you going with flush or mushroom thru-hulls? If flush, how do you plan to match/deal with the bevel in the hull? New thru-hulls/seacocks are on my list for my next haul out in May.

my hull currently has all flush thru-hulls.  i couldn't say whether this is standard or not.  unfortunately groco doesn't list the bevel angle or the distance from the shaft to the bevel.  it seems foolish to think the marelon ones i removed and the new bronzes are a match. 

after i get some measurements, if they match then i'll put flush ones back in.  which kind of stinks because the groco flush mounts are more expensive then the mushroom ones.  i'll probably pick up one of each, test fit them, and try to see if there is any impending disasters.  i'm really trying not to have to pay the fiberglass guy to re-fare the hull for any reason.  hopefully it'll all just work!

i hope to have the flush/mushroom question answered this week, i'll report back.  it was only just warm enough this past weekend for me to even get down to the boat and pull the old ones out.

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mdidomenico

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Re: raw water strainer removal
« Reply #14 on: February 24, 2018, 11:40:50 AM »

nuts...  apparently the marelon thru-hulls have a much larger flange.  now i'm soliciting opinions on the best course of action.

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