Mainship 430 Tank Vent Caps

[peterg]

Hi All -
My new to me 2003 Mainship 430 double cabin has several tank vents on the hull sides. The vent fittings have black plastic caps/covers that appear to screw on to the vent fitting - see attached pics. Some of the caps are missing. Does anyone know the manufacturer of the caps or vent fittings themselves? Looking to acquire a few of the caps. Thanks.
Peter

 

[Bacchus]

What are the sizes?
What tanks do they serve?
Are you looking for the fitting or the cap/plug?

They look like fill fittings / caps vs vents.
Are they mounted on the tank or deck?
The MS arts sticky has links & info for accessing many MS part photos. Unfortunately it is not searchable but you can scan thumbnail pics quickly and open the photos of any that look similar. The photos list the source as well as part info.

 

[peterg]

These are vents on the hull sides, about amidships. ID is about 3/4" and is threaded on the inside. I believe they are for the holding tank and fuel tank, there are a set both port and starboard. There is a screen embedded in the metal portion of the fitting. I'm just looking to replace the missing caps.

I will try to look thru the MS arts sticky links for parts.

 

[HeadMistress]

Facebook has a Mainship owners discussion site where you're most likely to find the answers you're looking for. You' ll have to join to read and post to it but they're a friendly group of people.

I have seen holding tank vent thru-hulls that are caps with slits in the bottom but I've never seen removable caps on open "bulkhead" fitting thru-hulls, so I suspect yours may have been something a PO has done, 'cuz I can tell you that you NEVER want to block a holding tank vent unless it's done just before being away from the boat for an extended period. If you join the FB MS group, I'd love to know what if anything you learn from those folks about them.

--Peggie

 

[Bacchus]

A Google search for tank vent ftgs shows some fuel vents with removable caps.
If you have access to the hull inside I would suggest replacing at least the holding tank vents completely with a straight mushroom vent. Save any usable caps for the fuel tank. Removing and spraying them w black paint will at least slow down UV degradation.

 

[peterg]

Perhaps I shouldn't have called these 'caps'. They are (presumably removeable) vent fittings to keep water out but still allow airflow.

I will see if I can figure out which is fuel and which is holding tank, to do what Bacchus suggests. I'm afraid these will be behind the fuel tanks on the interior.

 

[peterg]

FYI - the vent fitting I've been looking for seems to be a Perko 'P-trap splash guard', see link below. Not sure if I actually have the Perko P-traps, as the plastic fitting install on my boat (pic in prior post) is different than that shown in the Perko catalog (where the plastic guard is recessed). And the Perko P-trap seems like too fancy a fitting for Mainship to have used, unless perhaps it was installed by the PO.

Perko 063000499B | Fisheries Supply

Save More on Your Perko #063000499B PKO 063000499B SPARE CAP FOR 0630 BLACK P-TRAP at Fisheries Supply. Excellent Customer Service, Ready to Ship. Marine Supplies Since 1928!

www.fisheriessupply.com

 

[Bacchus]

That does look like it.
Boat mfg use what is available / from lowest cost sources so many parts are not exactly the same from year to year or even w/in yrs.
Google search of a picture is a worthwhile feature to use when unsure of mfg / source

 

[CaptainKrunch]

If you just want to cap them off, home depot plastic PVC caps will do...but if you need to vent them (like splash guards) you best find originals or copies I'd think.

 

[Drogers100]

Those are the fuel and fresh water vents. It appears they have discontinued that vent (I've spent many hours searching) so I placed a screen to prevent critters from entering and then covered them with a large clamshell. Looks great and allows me to pump the fuel a little faster.
Amazon.com

 

[HeadMistress]

Screens on the fuel and water tank vents are a good short term fix, but screens get clogged by dust , pollen, air pollution and corrosion. Replacing the original thru-hulls with standard "vent" thru--are the best permanent fix. But NOT on the holding tank vent!

Unlike fuel and water, sewage has to be managed (something boat builders have never shown the slightest interest in learning), which requires a vent that can "breathe" (freely exchange air with the gasses in the tank)--essential to preventing odor. So replace whatever is there now with a plain open bulkhead (aka "mushroom") thru-hull that accomplishes that and also allows you to prevent vent blockages by putting a hose nozzle against it to back flush the vent regularly, washing anything that's trying to set up housekeeping in it into the tank. Unfortunately backflushing the fuel and water tank vent lines would be a very BAD idea

--Peggie

 

[peterg]

The original venting caps are from Perko (part number PKO 063000499B), they can be special ordered thru a retailer (like West Marine or other), Perko will not sell direct to consumer. About $10 ea.

They easily twist off if you want to backflush the holding tank vent. But like Peggy said, it would be really bad to backflush the wrong one, and I'm not sure which is which.

 

[HeadMistress]

I'd use a plain ol' stainless steel bulkhead fitting...and if necessary fabricate a small plastic "waste" label that you can glue onto the hull directly above or below it. Might not hurt to label all three vents. You wouldn't want to mix up fuel and water either.

--Peggie

 

[porman]

Just a side note. The stock fuel tank vents are very low, only a few inches above the top of the tanks. The hose to them runs from the front of the tanks, sits on top of the tanks, and then goes to the vent above the rear of the tanks. When filling it's easy to get fuel in the vent hose and have it spill out the side. I raised the vents about 11 inches to eliminate the problem. I used stainless flush vents. You can get access to them by removing the engine air intakes.

 

[J.T kearney]

Just a side note. The stock fuel tank vents are very low, only a few inches above the top of the tanks. The hose to them runs from the front of the tanks, sits on top of the tanks, and then goes to the vent above the rear of the tanks. When filling it's easy to get fuel in the vent hose and have it spill out the side. I raised the vents about 11 inches to eliminate the problem. I used stainless flush vents. You can get access to them by removing the engine air intakes.

On my vent caps for my 1998 350 were made by attwood which i need to replace. Attwod was stamped on the remaining survivor .

 

[J.T kearney]

On my vent caps for my 1998 350 were made by attwood which i need to replace. Attwod was stamped on the remaining survivor .

Cheers J.T.