I am considering fitting a non return valve into the on breather pipeline to stop any potential water getting into the fuel system. The chances are remote but for £5 which is the cost of a 1/2 inch valve it seems worth the piece of mind.
When filling the tank the valve should be not be a problem. My only concern is when the engine is being run and fuel is being used will the pressure reduction cause the valve to close? What would be the likely impact.
Not sure about that John, isnt the breather pipe there to let air out when filling the tank and to let air in when the fuel is being used? I would think you want to maintain dual flow. The breather pipe should go to a high point before it reaches its exit to prevent water ingress.
Dear John
If you install a non-return valve and the movements of the yacht or the fuel in the tank cause it to close, the engine fuel pump will draw fuel from the tank for some time until it can not any more cope with the vacuum developing.
If you are concerned about getting in water through the breather line it is suggested that you modify the breather system to a safe one used on later models. For this you need to run a hose from side to side high up across the main bulkhead, and connect the breather line to it. I can make a sketch of the arrangement if required.
Kind regards
Lars
On my 47 the breather pipelines run all the way to the interior of the dorades on both sides of the main entrance. There are two non return valves there.
Do you know if this was a standard feature for the 47?
I have usually problems when filling the diesel from a gas station and the intake needs to be done at a very low flow rate to avoid spilling out. Is it possible that the pipe bend have been flattened? In case, are the other owners of 47' facing similar problems?
Thanks,
Matteo 45 grampus 47/016
The requirement to slow fill is certainly not limited to your 47. We have the same issue; even though there is a very straight filler hose run down to the tank. I suspect its just a relationship between flow rate and the length and diameter of the fill line.
(Deck always washed down with water before filling, some soapy water on hand to tackle any spills and patience!)
The requirement to slow fill is certainly not limited to your 47. We have the same issue; even though there is a very straight filler hose run down to the tank. I suspect its just a relationship between flow rate and the length and diameter of the fill line.
(Deck always washed down with water before filling, some soapy water on hand to tackle any spills and patience!)
Adrian
441
Adrian, do you have, too, no return valves on your breather pipelines? I suspect sometimes that my retirn valves are clogged. It is possible that an open breather pipe facing down inside the dorade would be enough to prevent water intake..
It is possible that this syphoning comes from the intake pielines, the diesel comes in fragging air and it generates a foam when there is a bend inside generating turbulence. I have seen that the majority of the other sailing boats do not have this problem when filling their tanks.
Matteo
I would suggest that the breather lines originally did not end inside the Dorade boxes, but on the outside. Would be interested to hear from other 47:s about this detail.
With today's environmental requirements it would be advisable to put a small bucket under the breather line end in order to collect any spill.
Fragging fuel coming out from the filler line indicates that the breather line is not able to evacuate the air fast enough. Check that there are no pockets in the breather line where liquid can collect, and no sharp bends or flattened sections.
On the older Swans the breather and filler hoses do not meet the present requirements, and it would be advisable to consider replacement, possibly increasing breather line size, as the fuel filling nozzles now have a higher rate of delivery.
Enclosed a sketch of the breather arrangement suggested for preventing water from entering. Needs to be located on a bulkhead.
Kind regards
Lars
PS
I got this error message when trying to upload
Allowed memory size of 41943040 bytes exhausted (tried to allocate 256 bytes)
Some strange problems, but here the sketch comes.
The horizontal hose terminations can be located in the recessed cove stripe, will then be less visible.
Lars
Guys thanks for the inputs. As we all know are boats are wet on deck when it gets windy and with the low free board we often get waves breaking over the deck.
I have now fitted the valve and venting air during filling the tank is obviously no problem as air is being pushed out. I have run the engine and to date no problems. At cruising revs I use about 3 liters per hour, max 5 liters per hour. So the non return valve needs to stay open when tank pressure is equalizing at this rate. The spring holding the non return valve open seems to be able to stay open under this pressure. The non return valve has been fitted inside the dorade at the point the pipe attaches to the chrome fitting which goes through the side of the dorade. The other end of the plastic pipe attaches to a copper pipe coming through the top of the deck all inside the dorade. Lars, you say things are now fitted differently. I would be very interested to understand what is now fitted to stop water getting down the vent.
I have noticed previously that the bore of the original through deck fitting diesel cap is a different size from the bore of the pipe on the tank. Worth checking if you have a slow filling problem.
Here is a pic of my 47 with the small round fittings ( vent on the underside) on the outside of the dorade box. the flexible pipe inside the box is curled up with the turns above the outlet - but by only 10cm or so. I had thought that these fittings were original? I am not aware we have ever had any water ingress gere.
Dear John
Thank you for the information. My comment about things fitted differently now referred to the sketch I posted above.
For your present arrangement I can think of two ways of reducing the risk of getting water in - put a small cap over the outside fitting in hard weather, and/or lead the breather pipe up inside the stainless guard to the upper level, with a termination there.
If you get water into the breather fitting now, and the non return valve closes, can you easily clean out the water? Otherwise the breather will stay closed.
Dear Rob
Thank you for the photo, confirms my thoughts about their original position. Would suggest that there is rarely solid water on deck to the level of the breather fittings, and they are protected on the aft side of the boxes.
Hello - could you tell me what the other things are (besides the vents) on the aft facing portion of the companionway Dorade boxes? I'm just curious. My boat has the holes remaining here and there from various pieces of original gear that are no longer present, this is one of those places. I just wonder what those are? Different subject, inspired by your picture: do you like your companionway spray hood, and are you glad it's there? Does it ever get in the way or give you any problems? I am thinking of getting one made up, and looking for feedback. I know I don't want a full dodger, which would take away from her looks I think. I wonder if the water the spray hood blocks (vs. just sliding the lid shut) is worth it?
Geoff,
my 411 has got a companionway sprayhood and I always considered it very useful. If it is open it makes entering and exiting a bit more tricky but when it rains or the sea is rough it positively permits to have more air inside. In some occasions I could let the Neco steer and stay well protected behind the sprayhood sitting on the upper step of the companionway stairs. It does not protect the cockpit but what it does is enough to fully justify its presence.
Moreover I am thinking of adding something similar to the fore hatch. At minimum the hatch cover designed by S&S for this purpose.
Daniel, 411/004
The other fitting on the aft face of the Dorade Box is a harness clip on point. Helpful when you want to clip on before you climb out of the companion way. It is top hinged, and when not in use is held by the soft red rubber button which stops it rattling! Unfortunately the newer type harnesses have flat clips which do not fit through the holes. We also have the same fitting in the cockpit below the helmsman seat.
As for the spray hood, it is invaluable, I could manage without it. It helps protect the Nav Table below , a great place to view forward when in rough weather, etc etc. To gain access, it simply folds flat and is "sprung loaded" by the 2 bungee straps which are arranged to make use of the "cam effect" of the frame design.
The 47 has a second companion way aft in the cockpit, and here we have a larger sprayhood which you can sit under. This is also invaluable - we spend many hours crossing the English channel in true english weather!
