raw water strainer removal

[Dave Spencer]

I'm with you domenico!  I was thinking of starting to gradually replace my through hulls, but I didn't have any interest in fibreglass work to fair the hull to match the smaller flanges so I have left them as is.  My half hearted internet search for extra wide flange through hulls from a few years ago didn't yield any positive results.  I will be keen to see if others have a source for the wide flange through hulls.

[mdidomenico]

poking around the internet it looks like buck algonquin makes a 3/4" bronze flush thru hull that has a 2-1/2" flange.  the marelon flanges come in at 66mm or ~2-5/8" , there might end up being a 1/16" gap between the seat of the flange and the hull.  i'm not sure if that's okay or not, there's usually some squeeze out of glue, presumably the glue will fill that void

i ordered one to see how it fits in the hull and whether it'll thread cleanly into a groco flange.  if it works, that'd be great.  if not, i'm worried my only options are to either get new marelon fittings or fair the hull smooth and use mushrooms.  my confidence with fairing the hull is pretty low, but i'll have to 'internet it' and see what is really involved in filling a big hole.

nothings been fitted to the hull yet, if anyone see big red warnings signs, please let me know.

[Noah]

Mideomenco- sorry you are having valve fit problems. Thought that might be a issue when I asked in a previous post about how you were going to deal with the taper (flush fit).  I am looking to replace my thru hulls and valves as well, but don't have the advantage of being on the hard for a extended time. I have to orchestrate all bits and pieces prior to haul out. I am considering Forespar Marelon OEM Series 93 over standard Marelon flange with backing plate—decided against bronze. In either case, knowing the outside diameter of my various flush through hulls would be a plus in planning/ordering parts ahead of time. What is the diameter measurement of your existing Marelon flush tapered flange/heads?  Do they match the current available Marelon flush head size(s)? Or will you still need to fill, drill, regrind, etc.?

[Dave Spencer]

Hi Noah,
I think he said the the flange OD was 66mm  (2 5/8") which is consistent with what I measured a few years ago.  This pic shows the head sink drain.  It would be great if there was a readily available source for Marelon wide flanges. 

By the way... I love your comment "...don't have the advantage of being on the hard for an extended time."  What a polite dig at us northern sailors who have the privilege of carefully examining our hulls on the hard for months at a time while some poor sailors such as yourself have to sail your boats all 12 months of the year!   

[mdidomenico]

What is the diameter measurement of your existing Marelon flush tapered flange/heads?  Do they match the current available Marelon flush head size(s)? Or will you still need to fill, drill, regrind, etc.?

the outer diameter of my old marelon fittings is 2.66in for both the 1/2" and 3/4" fittings.  it's hard for me to say whether new forespar fittings are a direct fit without actually having one.  if we look at the chart they show, for series 250 fittings, different measurements for 1/2" and 3/4".  mine are not.  the 1/2" and 3/4" flanges are exactly the same, they only varied the threaded portion in diameter. 

this is probably because the originals are not from "forespar" but rather have stamped on them "r.c. marine".  according to the history page at forespar, forespar bought the tooling from rc marine in the 80's.  if i had to guess as forespar got smarter in making the parts they re-tooled at some point and changed all the dimensions from the rc marine originals.  if that were true, depending on how detailed the records are at catalina, i'd bet they could tell us exactly when that happened, as i imagine they would have had to modify the hull mold.

anyhow, using just the 3/4" fittings as an example my outer diameter (value A) is 2.66in or 2-5/8", the chart for a 3/4" thru shows 2.43in or 2-1/2"  at first blush this might not be an issue at all, maybe some space for the glue to seep out and form a good bond.

the groco bronze fitting is 2", so that gap is much to large to fill with glue.  i'm hoping the buck alonquin fitting at 2-1/2" will fill the gap enough that sika-flex will take up the 1/16" gap around the fitting and all will be good.  i suspect the same "working theory" could apply to the marelon fittings

or it could be a disaster, i have no idea.

[Noah]

Thx guys! Good info. My "out of the water comment" wasn't a passive aggressive dig. Really! It cuts two ways. Yesterday I was crunched up in the forepeak changing  the anchor locker drain hose and instead of the hose coming off, the old nylon thru-hull at the bootstripe snapped off! Today, I will be installing a new marelon one. In the water! How? Maybe laying face down, on the dock?, in a dinghy?, who knows...? But right now I am seeing daylight and water! BTW- Ron, it is a 3/4 in thru-hull, not 1/2 in. !

[Ron Hill]

Noah : If it is a 3/4"OD thru hull, the ID might only allow a 1/2" dowel?

A thought

[Noah]

Continuing to highjack this thread, sorry.  Successfully installed my anchor locker drain thru hull at the boottop/waterline.  I used Marelon to replace the busted nylon one.

The thru hull is 3/4 and barbs to use a 3/4 ID hose.

My plan was to back the boat into my slip and hang off the dock to reach the thru-hull but, it was blowing 20 kits— too risky with almost no daylight between the two boats.  So I pulled my bow over to his stern, catty corner in the slip, and hung off his swim step.  Went pretty quickly with me on the inside of boat and my son-in-law holding thru-hull from turning outside, with an improvised too; a cold chisel with Vice Grips clamped on as a handle.

[mdidomenico]

Continuing to highjack this thread, sorry.  Successfully installed my anchor locker drain thru hull at the boottop/waterline.  I used Marelon to replace the busted nylon one.

actually it's okay, those pics were helpful, the anchor locker is next on my list.  my thru-hull there is busted off on the outside and the locker is full of leaves and crap.  all happened before i bought the boat.  but the pics at least let me see what i'm in store for... :)

[Dave Spencer]

Great pictures Noah.  Thanks.  I sometimes lie awake at night thinking of ways my boat could sink.  The anchor locker drain low at the bow and the bilge pump discharge fitting low at the stern both come up frequently.  I think I'll order the appropriate through hulls and some hose so I can get going on those two jobs while I can do the work at convenient shoulder height on dry land.   

[mdidomenico]

even though i run the risk of totally jinx'ing it.  i think I have a solution.  the Buck Alonquin thru-hull arrived today and it's actually like 1/32" or 1/64" larger then the marelon one.  it seems to thread in the groco flange just fine.  so, this might just work out...

[mdidomenico]

in fact, i just measured the differences with a micrometer.  the BA thru-hull is ~1mm larger in diameter and it's ~1.5mm thicker in the flange over the marelon one.  so all in all, should be pretty close fit or at least close enough...

[Noah]

Nice! Do the bevels match for all your thru hull sizes?

[mdidomenico]

Nice! Do the bevels match for all your thru hull sizes?

they're close.  the marelon (from forespar) bevel is shown at 53 degrees, the BA is shown at 45 degrees.  i'm hoping that since the BA thru-hull has a shallower angle that the small gap difference will just fill in with sikaflex.  i'll be down at the boat this weekend, I'll know pretty quick if it doesn't fit, here's hoping...

[mdidomenico]

looks like we might have a fairly decent fit.  seems to line up pretty well around the flange.  i still have some sanding to do to remove the excess caulk and paint still in there.  but a little cleanup of the holes and i think we'll have a "good enough" fit.