Hose Fittings & Clamps with thru hulls?

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Bob S

Bob S

.
Sep 27, 2007
1,813
Beneteau 393 New Bedford, MA
I am changing over my sea strainer from the plastic OEM to a bronze Perko. Catalina uses Marelon thru hulls. They used barbed fittings that are probably nylon and very thin walled. Using two hose clamps has really deformed them. I decided to buy Groco bronze barbed fittings for this upgrade. I'm not happy with the way these fittings are made. It appears for economy purposes Groco has casted duel barbs for use with either 1/2" or 5/8" hose. If you cut the 1/2" barb off like I assume you are supposed to do there isn't enough barb length to double clamp the hose. If I leave it on the ID is too small. The ID's are casted @ 1/4" on the 1/2" barb and 3/8" for the 5/8" barb (1/8" wall). I bought 316 SST hose clamps that are 1/2" wide and the barbed length is roughly 5/8" so it is impossible to use two clamps as is recomended.

Opinions?
 

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sailingdog

sailingdog

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Oct 22, 2008
3,502
- Telstar 28 Buzzards Bay
Why not use the straight ones that look like this:



Image courtesy of HamiltonMarine.com
 
Ron20324

Ron20324

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Jan 22, 2008
8,050
Beneteau 323 Annapolis MD
bsmith, there are thinner clamps available than 1/2 wide. I was just looking at those Groco's for my own project and I'm sure there is one that does not have the step-down sizes, but maybe not. You're trying to use 5/8 hose?
 
Bob S

Bob S

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Sep 27, 2007
1,813
Beneteau 393 New Bedford, MA
I am using 5/8 hose and Dog, I bought 2 straight and two elbows. They're both cast the same way. I will try finding thinner hose clamps.
 
Bob S

Bob S

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Sep 27, 2007
1,813
Beneteau 393 New Bedford, MA
Sailingdog, if you look at that picture closer you can see the step down on that barb too.
 
sailingdog

sailingdog

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Oct 22, 2008
3,502
- Telstar 28 Buzzards Bay
bsmith said:
Sailingdog, if you look at that picture closer you can see the step down on that barb too.
Click to expand
Yes, the photo ones are dual size, but the ones I just bought are not. They have plenty of length for two hose clamps.
 
Shell

Shell

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Sep 26, 2007
138
Catalina 30 standard JC/NYC
Just don't use ss clamps from Home Depot.
A few years ago, I replaced the hose off the exhaust manifold so I decided to replace the stainless clamps. The original clamps from my Catalina were dirty, no rust. I cleaned them up for spares. Replaced them with ss clamps from Home depot.

Next season, when I commissioned the boat the Home Depot clamps were rusted. The original clamps wre perfect.
 
Bob S

Bob S

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Sep 27, 2007
1,813
Beneteau 393 New Bedford, MA
Shell,

I bought everything I needed from McMaster Carr. The hose clamps are 316 SST including the screw.
 
MrBee

MrBee

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Dec 30, 2008
425
Irwin 34 Citation Middle River, Md.
A lot of the cheapo Stainless clamps at hardware stores and big box stores have NON stainless screws in the stainless clamp part. Check them with a magnet.

Bee
 
sailingdog

sailingdog

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Oct 22, 2008
3,502
- Telstar 28 Buzzards Bay
Actually, the cheaper, non-marine grades of stainless steel (martenisitic vs. austenitic) are magnetic.

MrBee said:
A lot of the cheapo Stainless clamps at hardware stores and big box stores have NON stainless screws in the stainless clamp part. Check them with a magnet.

Bee
Click to expand
 
Maine Sail

Maine Sail

.
Feb 6, 1998
11,760
Canadian Sailcraft 36T Casco Bay, ME
Fittings

bsmith said:
I am changing over my sea strainer from the plastic OEM to a bronze Perko. Catalina uses Marelon thru hulls. They used barbed fittings that are probably nylon and very thin walled. Using two hose clamps has really deformed them. I decided to buy Groco bronze barbed fittings for this upgrade. I'm not happy with the way these fittings are made. It appears for economy purposes Groco has casted duel barbs for use with either 1/2" or 5/8" hose. If you cut the 1/2" barb off like I assume you are supposed to do there isn't enough barb length to double clamp the hose. If I leave it on the ID is too small. The ID's are casted @ 1/4" on the 1/2" barb and 3/8" for the 5/8" barb (1/8" wall). I bought 316 SST hose clamps that are 1/2" wide and the barbed length is roughly 5/8" so it is impossible to use two clamps as is recomended.

Opinions?
Click to expand

5/8" hose barbs for below waterline use is very tough to get. Many some manufacturers no longer even make stuff below 3/4" and this is for a reason. I would urge you to go up to 3/4" then you can order a Groco fittings with a 1.38" long barb or more. If your intake is 1/2" now would be a good time to upgrade to at least a 3/4". I often upgrade my engine intakes to 1" to prevent clogging and to facilitate easier snaking..

Straight Groco:

PHT-750 = 3/4" / barb length = 1.38"

I do not like anything smaller than 3/4" on intake as it has a tendency to plug more rapidly.

90 Degree Groco:

PTHC-750 = 3/4" / barb length = 1.5"

Groco Online Fittings Catalog (LINK)


I strongly advise the use on non-perforated AWAB style hose clamps over the Ideal style too.

Please DO NOT use home center fittings they should be marine rated bronze!

Home Center brass barb:
 
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