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Fuel compartment ventilation

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jerlim
Master Marine Consultant

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USA
1484 Posts

Initially Posted - 07/22/2006 : 20:57:19

The 1980 SK/SR I just bought has a +/- 4' length of 3" flexible tubing (think vinyl dryer hose) leading from the inside of the port vent and simply hanging down into the bottom of the fuel compartment/locker, sort of down to the bilge.

I'm unclear on the purpose; is the hose to direct fresh air into the bottom of the compartment, as gas fumes may accumulate there? I need to run the gas line from the tank to the motor through the hose, and therefore compress the length to +/- 1'-6". Any opinions or advice?

As always, a collective "Thank You" to everyone on the forum for your incredibly valuable insights and wisdom!

Best - Jerry

Jerry

Edited by - on

wmkoines
1st Mate

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56 Posts

Response Posted - 07/23/2006 : 06:25:43

You should have two 3” flexible hoses, one as you describe and the other one is attached to the other side and leads to the bottom of the “Pit”. The two hoses act to bring air in and out. I have a hole that my gas line passes through with a rubber covering, but I wouldn’t think passing the fuel line would make a difference.

I have recently replaced the tubing when I found holes from wear and rubbing on the bottom. I also purchased a PVC coupling for the bottom hole to get a better fit and seal the bottom better. I was finding some gas fumes getting into the cabin from the hole in the wall bottom.

Edited by - on

Buzz Maring
Master Marine Consultant

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USA
1768 Posts

Response Posted - 07/23/2006 : 09:41:00

Hi Jerry,

It sounds like you have the same "dumpster" fuel locker/lazarette that I've got on my 1977. In later models the fuel locker is separate from the lazarette, and it is easier to route the fuel line from the tank to the outboard.

When I bought my boat, the PO had removed the ventilation hose and routed the fuel line up through the metal ventilation cowl (sorta' like what you plan to do, except you're going to keep the ventilation hose, right?). I decided that Catalina must have put that ventilation system there for a reason, so I looked for another way to route the fuel line.

I ended up drilling a hole through the transom, and I installed a marelon fitting for the fuel line to pass through. It works fine, and the ventilation system is now intact, doing whatever Catalina intended for it to do.

I tried to post a photo of the fuel line coming out through the transom, but I can't get Shutterfly to work this morning. I'll try again later ... I know a picture is worth a thousand words.

There's more than one way to skin a cat ... 'hope that helps ... good luck!

Edit: 'Looks like my computer was at fault ... after a reboot, Shutterfly is working OK. Here is a photo of the fuel line coming out through the transom:

Edited by - Buzz Maring on 07/23/2006 10:06:11

sweetcraft
Admiral

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USA
816 Posts

Response Posted - 07/24/2006 : 00:30:19

The vent system is to bring the boat into compliance with regulations with a portable tank stored below deck. I think that the tank has to be metal. I use a metal tank with a fire resistant fuel line directly connected to tank and have a hole with a boot for all the lines and controls and the fuel line. When cruising I have two tanks and two fuel lines through the hole, all fittings to outboard are outside the hull. I added to the vent system a power inline vent fan which is run for several minutes before the start, regulation? A sniff of the compartment before start is also what I try to practice. Later C25 have much better design. Vent and sniff.

Edited by - on

Frank Hopper
Past Commodore

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Pitcairn Island
6776 Posts

Response Posted - 07/24/2006 : 06:38:25

Captain Maring, you are here-by commanded by a Flag Officer to buy a new motor mount, you may spend up to $340. Please inform your spousal unit that you have no choice due to this being a direct order. Carry on.

Edited by - Frank Hopper on 07/24/2006 07:02:54

jerlim
Master Marine Consultant

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USA
1484 Posts

Response Posted - 07/24/2006 : 07:28:56

Jim,
Thanks for the insight, "vent and snif" is great advice. I wondered about the powered in-line vent fan, any concern about electrical motor sparks?

Edited by - on

Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 07/24/2006 : 08:14:21

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by fhopper@mac.com
 Captain Maring, you are here-by commanded by a Flag Officer to buy a new motor mount, you may spend up to $340. Please inform your spousal unit that you have no choice due to this being a direct order. Carry on.
<hr height="1" noshade id="quote"></blockquote id="quote">

Hopefully Buz has no more than a 4hp auxiliary!

Edited by - on

StSimon
Captain

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USA
298 Posts

Response Posted - 07/24/2006 : 18:40:52

<blockquote id="quote">quote:<hr height="1" noshade id="quote">There's more than one way to skin a cat<hr height="1" noshade id="quote"></blockquote id="quote">

What you left out is that you can can count on the cat not liking any of them.

Edited by - on

sweetcraft
Admiral

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USA
816 Posts

Response Posted - 07/25/2006 : 00:32:34

The blowers used are ignition protected and approved by CG, bought mine at Wally world. WM #http://www.westmarine.com/webapp/wcs/stores/servlet/ProductDisplay?storeId=10001&langId=-1&catalogId=10001&classNum=12111&subdeptNum=302&storeNum=12&productId=120672
Safety first, a fire at sea can ruin your whole day.

Edited by - on

Jasonconradt
Deckhand

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USA
14 Posts

Response Posted - 08/22/2006 : 13:43:15

This may sound stupid but where are people mounting the blower and which way should it vent? My engine is mounted on the port side, the portside vent is facing towards the bow, the starboard vent is facing aft. Both hoses are in pretty good shape however the "pit" was full of water and debris, which I pumped out then used a washdown hose and deck brush to scrub and get most of the gunk out. Obviously this area needs to be kept dry if my plan below is to work, otherwise rising water will get find its way into the starboard vent hose. Seems like a very poor design overall but it's what I've got to work with

My initial thought is to draw air from the portside vent by installing somewhere between the "pit" hose entrance and the starboard vent, exhausting the fumes aft and starboard. I also am considering drilling some ventilation holes in the wood floor of the "pit" to allow the heavier gas fumes an easier path to the starboard vent hose. Does this make any sense? Or should it be the other way around - mount on the port lazarette, pull air from the starboard aft side? This seems counterintuitive because then it's dumping all of the fumes back into the cockpit.

Also the PO has both 3 and 6 gallon plastic tanks in this storage compartment, so this would be out of compliance with USCG regulations even with a blower?

Edited by - Jasonconradt on 08/22/2006 13:45:33

Frank Hopper
Past Commodore

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Pitcairn Island
6776 Posts

Response Posted - 08/22/2006 : 14:19:25

Jason, I would punt the location and simply put my tank out in the cockpit. Many designs have them there. There are "cooler" tie down brackets that are four molded floor corners and a strap that are cheap and would lock a tank in place. I think the internal fuel platform is much better suited to a sub and amp installation.

Edited by - Frank Hopper on 08/22/2006 14:25:07

djn
Master Marine Consultant

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USA
1561 Posts

Response Posted - 08/22/2006 : 14:51:32

Hi Frank, I was thinking about doing just this but can't really think of a place to put he tank. Any suggestioins? Cheers.

Edited by - on

Jasonconradt
Deckhand

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USA
14 Posts

Response Posted - 08/22/2006 : 14:57:42

Interesting idea but ideally the tank will remain out of sight / mind due to small children frequently being aboard. Additionally, I wouldn't want to keep the fuel tank in the cockpit 24/7/365 - it'll get stowed in the port locker when we're not using the boat and thus generate some gas fumes that really should be vented. Don't misunderstand - you've got a viable option for many, but I'd really like to tackle venting this properly, provided it's not a royal pain in the behind.

Edited by - on

Frank Hopper
Past Commodore

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Pitcairn Island
6776 Posts

Response Posted - 08/22/2006 : 15:15:00

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by djn
 Hi Frank, I was thinking about doing just this but can't really think of a place to put he tank. Any suggestioins? Cheers.
<hr height="1" noshade id="quote"></blockquote id="quote">

For me a 3 gal tank at the transom would not cause a problem, I have kept large Oscar coolers there. Many boats have a simple hatch lid that hinges from the transom. A top and a forward face. The hatch can even have a locking latch. Take a piece of cardboard out to the cockpit and put a simple 90 degree bend in the middle, figure out the demensions with that. It would be a great fiberglass project to make or even cool out of teak.

Edited by - on

Champipple
Master Marine Consultant

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USA
6855 Posts

Response Posted - 08/22/2006 : 16:40:33

A few things to add here:

First, I route my fuel line the same way Buzz does. A simple through hull fitting. I also route my electric cables for electric start through a second through hull.

The cowlings bringing air into and out of the cabin are just to maintain ventilation albeit they do vent the fuel locker area and keep the boat in code. They were part of the design before ventilation was a requirement. Some owners between late 78 and when they switched out the tank in the early 80's may be required to have a certificate of compliance, but I am fairly certain that only applies to inboards.

The outboard engine is obviously not internal, no blowers are needed as would be if the engine was an inboard regular gas engine. Not to mention, you need to open the compartment to squeeze the priming bulb prior to starting anyway, that alone brings in more air that a blower ever would in such a short time.

Last - The gas can is not required to be metal. Plastic is more than sufficient.

Blowers aren't necessarily a bad thing, especially since they would bring peace of mine. (not to be confused with a piece of my mind) Personally, I think they would be overkill.

You might check some of the other requirements (minimum requirements) as listed here on the USCG aux Vessel Safety Check Form.(see below)

As usual, some states may have opted to enforce rules stricter than that of the Feds.

http://forms.cgaux.org/archive/a7012.pdf

http://www.vesselsafetycheck.org/what_is_vsc.asp

Edited by - on

aeckhart
Master Marine Consultant

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USA
1709 Posts

Response Posted - 08/23/2006 : 18:38:08

I carry a six gallon metal fuel can in the fuel compartment on my 88 wing, and a 12 gallon plastic tank in the cockpit under the tiller when cruising. I've been looking for a tie-down method. Thanks Frank.

Edited by - aeckhart on 08/23/2006 18:38:35

jerlim
Master Marine Consultant

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USA
1484 Posts

Response Posted - 08/23/2006 : 20:17:29

My (1980) port locker does not connect/vent/feed thru to any other spaces, it is sealed from the cabin. The port cowling does face forward, passively directing air into the locker depending on ambient wind and/or our travelling. The starbord aft facing cowling draws whatever fumes/aromas accumulate in the pit only when underway. I'm just going w/ the vent and sniff approach.
Jerry

Edited by - on

djn
Master Marine Consultant

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USA
1561 Posts

Response Posted - 08/23/2006 : 20:26:37

Hi Al, I am not sure if my 1977 aft cockpit is the same as yours but I would not mine getting 12 gals on the boat. What is the size of that tank?

Edited by - on

sweetcraft
Admiral

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USA
816 Posts

Response Posted - 08/24/2006 : 09:39:08

I like the idea of the plastic tank in the cockpit for cruising which is better than the 2nd tank below deck. I installed the power vent close to the vent facing aft with a panel switch. The fuel lines are now fire resistant and clamped to the tank and long enough to exit through a booted hole high on the transom which also are used for the engine controls. The quick connect fittings are all outside the hull so no drips inside the compartment; this took years to figure out. I also have installed a floor in the 79 in sections which have allowed the second tank to set flat on carpet with all the other items. Used the end of one of the engine mount bolts for attaching straps for the tank on the shelf. I have also learned to check the gaskets on each tank cap for both the vent and tank as they can develop cracks over night. Do you close the vent when sailing with motor tilted to stop burping gas into the compartment?
Just a few thoughts off the top of my head to avoid that saying a fire at sea can ruin your whole day.

Edited by - on

Jasonconradt
Deckhand

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USA
14 Posts

Response Posted - 08/24/2006 : 12:09:25

Thanks Jim, that's just what I'm going to do re: connecting the blower to the aft hose and wiring a switch. Did you run the switch to the main DC panel area or did you put something in the cockpit? Do you have any pictures of the fuel tank arrangement described below? Having a hard time visualizing and would appreciate a picture if you've got them. Irrespective of moving the second tank into the cockpit, the primary 3 gallon tank is going to remain on that ledge in the port locker. I'd like a blower to vent it out properly, seems like relatively cheap insurance against something bad happening - $50 and a little bit of time is no big deal imo.

Jerry - so you're saying the 1980 doesn't have a second vent hose in the port locker, underneath the wood floorboards that cover the "pit"? I just figured out that's where the hose from the starboard deck cowl led after cleaning out the "pit" last weekend.

The port locker is semi-contained against fumes entering the cabin in my 78. There is a rubber weatherseal that looks like faux wood surrounding the "wall" between the quarterberth and the port cockpit locker, but it's probably the original weatherseal and needs to get replaced eventually. This is on the list of projects. Has anybody done this job before and have any insight into a good material for the task? As a temporary measure, I might cleanup the wall from the locker side, then shoot some of that canned flexible foam all the way around. Thoughts?

Edited by - on

oldsalt
Admiral

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USA
578 Posts

Response Posted - 09/04/2006 : 07:56:52

Regarding fumes and steel versus plastic fuel tanks:

On my '83, the fuel tank is segregated in a locker that is completely sealed from the bilge area and I've always used original equipment OMC steel fuel tanks.

For some reason, unknown even to me, I preferred these tanks over plactic aftermarket models even though they have the drawbacks of costing an arm and a leg and rusting over time, and after 23 years, I'm on my second tank.

Last season when I was checking out my boat's systems I noticed that a very small "pinhole" had rusted right through the top of an otherwise shiny, perfectly brand new looking tank. Being that my tank is located in the totally isolated locker, I repaired the pinhole by simply screwing a # 8 pan head parker screw into the hole, which made a tight seal.

After that episode, if I had the older style non isolated fuel locker, I'd feel more comfortable with a plastic tank, and in fact my next tank will be plastic.

Back in the mid '80s, I had the experience of seeing a fairly new power boat explode, and seeing the two young ladies aboard it thrown overboard like rag dolls. Unfortunately, they were both horribly burned althought they did survive.

Since that time, I'm very wary of gas fumes in the boat or the use of propane or butane camping type stoves below decks.

It's easy to unwittingly fill the bilge with gas fumes by refilling the onboard portable tank from a gerry can while the hatchboards are removed. The gas fumes being heavier than air, will flow like an invisible river right down into your boat if the wind is blowing in the right direction.

Unless it's "sucked out" by a bona fide blower system, gasoline fumes, butane or propane in the bilge stays there and accumulates over time.

It never leaves.

Edited by - oldsalt on 09/04/2006 07:58:23

sweetcraft
Admiral

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USA
816 Posts

Response Posted - 09/04/2006 : 23:38:01

I'll work on some of the pictures tomorrow to see if they can better explain some of the things I have done and experienced. I have had all the panel removed before when working to install insulation around the place that was supposed to be a ice locker and saw a lot. There is no way you can seal the storage locker as the vent hose from the port side is rough cut into the lowest place in the locker and the space at the aft end is open to the bilge and the liner has spaces between it and the hull, so this is way I felt it was important to use a blower. I'll go down to the boat early tomorrow and get the pictures.

Edited by - on

jerlim
Master Marine Consultant

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USA
1484 Posts

Response Posted - 09/05/2006 : 13:09:26

Mark,
Chilling advice, very well said. I've been filling a plastic tank from a gerry (plastic) can. In the future, I'll be sure to pull-out the fuel tank, into the cockpit, and fill from the gerry can AND with the hatch closed!
Jerry

Edited by - on

Daniel
1st Mate

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78 Posts

Response Posted - 09/05/2006 : 16:58:52

Hi:

I have a 1980 (up for sale, incidentally). The port vent hose is led forward above the fuel compartment/stowage enclosure, ending portside just behind the plywood panel where the wiring, etc. is mounted. The cowl vent is directed forward. There is also a stainless grating (air vent) in the port aft seat back just above where the fuel tank platform is located
The stb vent hose leads down under the aft berth to a hole in the bottom center of the fuel compartment enclosure. The cowl vent is directed aft.

I think the idea is that fumes are heavy and sink, so will be directed into the stb hose to exhaust out the stb side as air is forced in the port cowl vent. I believe around the time this boat was built the regs changed, requiring the fuel compartment to be isolated from the interior (more isolated than on my boat).

Edited by - on

sweetcraft
Admiral

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USA
816 Posts

Response Posted - 09/05/2006 : 22:36:29

I am working on the pictures and saw my above the deck vent caps and I glued in an ABS pipe fitting. This was done years ago so that splashed water on the rail from washing or sailing with the rail under would keep most of the water from entering the boat's vent system, something like a dorade box (did I spell that right?). Now back to the pictures.

Edited by - on

dlucier
Master Marine Consultant

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Virgin Islands (United Kingdom)
7583 Posts

Response Posted - 09/06/2006 : 09:25:34

To keep water from flowing into the port side clam shell vent, I fabricated a one inch high dam out of stainless steel that fits in the opening of the original vent.

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