Mushroom or Chamfer On Though Hulls

[bradh]

On below the water line through hulls, was Ericson consistent in the type of sealing surface they used? I can not tell from the exterior as they are flush to the hull and most likely original. If I do pull the trigger, I do plan to remove them before ordering replacements to verify.

Thanks,

Brad

 

[davisr]

You might find this article of use. Given the age of your boat, it's possible you have Buck Algonquin through-hulls. As I explain in this article, present-day Groco through-hulls, which are common, do not have the same flange diameter as Buck Algonquins. I opted for Groco, but it required a lot of work to resize the holes to accommodate the flanges.

Roscoe

http://www.ericson25.com/2013/11/through-hull-replacement-part-2.html

 

[toddster]

That's good to know Roscoe. I only hope that I can remember this thread at the next haul-out.
During my re-fit, since time was short, and I was at the end of a long mail-order chain, I just cleaned up the old ones and replaced them, using new ball-valves but still with mis-matched threads. Just as they had been for 40 years previously. Given your report, I would order the Buck Algonquin's next time.

But. One other problem that came up, in replacing the old original gate valves with ball-valves, is that there is not enough altitude for them in the original locations under the head and the settee of my boat. I had to add 90° Ells between the through-hull and the valve. Obviously this would not be possible with the BA brand. Hmm...

I did replace the old chamfered speed sensor with a new mushroom-type one. It was also a larger diameter, so I had to - carefully - enlarge that hole. Which eliminated the problem of what to do about filling the chamfer.

 

[bradh]

Jackpot!

Can't say enough thanks. Exactly the info I was looking for. I too think I will most likely go with the BAs, but that only on a quick read though of your article.


Thanks,

Brad

 

[Loren Beach]

Valve Choices

Can't say enough thanks. Exactly the info I was looking for. I too think I will most likely go with the BAs, but that only on a quick read though of your article.

Thanks,
Brad

Plan B, as it were:
If you need a close-fitted right angle exit, have a look at the Forespar seacocks. These replaced the older RC Marine type that Ericson installed in the 80's and are far far stronger. I changed over to these in 90's when they were they 'new design product' and they work fine today. Serviceable from inside.

If you are concerned about getting the right chamfer fit for the outside piece, consider doing what we did.
The yard assembled the whole inside valve body on top of the backing plate, and bedded it to the hull with thickened epoxy. After this kicked they ground off the outside flange smooth with the hull surface.
Our boat did have the original recessed thru hull face, BTW.

This will reduce drag and make your hull a tenth of a nano knot faster, too!

While they still refer to these as "OEM" products, our local boat yard routinely stocks them.
http://www.forespar.com/OEM-Valves.shtml

I am not sure that they are for sale through retail chandlers, though.

No worries about electrolysis, either.

Loren

ps: one of ours: http://www.ericsonyachts.org/infoexchange/showthread.php?551-New-Strainer-amp-Thruhull&referrerid=28

 

[toddster]

Oh, one more issue with these through-hulls, I've "recalled" by looking up my old blog post.
The intakes on my 1970 boat are 1/2" NPS. Neither Buck Algonquin, nor anybody else makes 1/2" through-hulls or seacocks any more. The only upgrade path is to re-drill and re-chamfer the hole to accept the 3/4" size. This was the actual "last straw" that caused me to just re-use the old ones.

 

[bradh]

May end up with a couple types....

All great info. I have 5 through hulls below the water line. From your descriptions, 4 seem to be relatively straight forward (just tempted fate with that statement), the 5th sounds to be the problem child. It's the water intake for the engine and as toddster points out, it is a 1/2". And as Loren points out, it's probably going to need to be a 90deg because of tight clearance with the cabin sole. So I am thinking BA for the 4 due to the chamfer compatibility. For the 5th, I did notice that there is a 1/2" Forespar with a screen.

Loren - when you say they ground off the outside, this was on a chamfer Forespar through hull (and it was still slightly raised)?

Brad

 

[Loren Beach]

All great info. I have 5 through hulls below the water line. From your descriptions, 4 seem to be relatively straight forward (just tempted fate with that statement), the 5th sounds to be the problem child. It's the water intake for the engine and as toddster points out, it is a 1/2". And as Loren points out, it's probably going to need to be a 90deg because of tight clearance with the cabin sole. So I am thinking BA for the 4 due to the chamfer compatibility. For the 5th, I did notice that there is a 1/2" Forespar with a screen.

Loren - when you say they ground off the outside, this was on a chamfer Forespar through hull (and it was still slightly raised)?

Brad

Raised as I recall, but not really relevant, because this part was ground off smooth. One other wrinkle was that the factory location for the raw water intake on the Olson was under the galley counter and then the hose wandered aft through some holes in the "grid" to the pump on the engine. I had that new intake moved aft and close to the centerline, under the front of the aft berth. Lots more room there.
Old hole was patched with layers of glass and epoxy after edges chamfered.
(Winterizing the engine has been 1000% easier since making that change, also!)

One thing about those external "screens" - they provide a place for trash to clog them and have to be cleared by diving. Not good. :0
Strictly IMHO, but I would much rather have stuff go on into my (added) Groco strainer where I can get at it on the inside of the boat.

And... even one more thing, if you search the thru hull threads here there is one with a great installation of new bronze thru hulls on an E-35-2 belonging to John Moses. Lots of pictures.

As to the old 1/2" thru hull -- just over-bore to the modern standard "small" standard of 3/4".
Regards,
Loren

 

[toddster]

Now, it occurs to me to check the dimensions of the chamfered head. If the only difference between 1/2" and 3/4" in the Buck Algonquin fittings is the stem diameter, then enlarging that central hole would be relatively trivial. Although if you need a 90 below the valve, you're still up the creek.