Ventilation for cruising yacht

[mhember]

Hi,

Our Endurance 40 has Plastimo dorade vents.
(Plastimo 16933 Dorade Box Cowl Vent - 205 x 335mm)

These have proven less than ideal; they don't ventilate the boat especially well and in any sort of upwind weather we have to plug the vents as they let in rather more water than I'd hope.

I think they have been fitted the wrong way around which does not help. Finally, they have not proven very robust and the occasional passing sea boot tends to crack the screw holes.
I'm looking for a recommended replacement; I'm concluding that Solar powered ones will not be sufficiently weather proof, and ideally I want something lower profile probably with a built in stopper that can be shut when needed. I suspect I'm going to need to add a 12v fan in the cabins where we need a bit more air when occupied.

Anyone got any suggestions for good, robust, low profile vents?

Thank you!

 

[William_H]

A dumb question perhaps but aern't those vents meant to be rotated depending on conditions? ie face forward when on anchor providing air into cabin. Face aft when sailing up wind to draw air out of cabin. ol'will

 

[Dellquay13]

I’ve fitted solar vents to several boats and found them to be very effective. I have always used the stainless low profile ones with integral rechargeable batteries, and not found them any more prone to leaks than the regular passive vents they have replaced. They usually come with an internal cover when you want to stop any airflow at all.

Looking at the picture solar vents might not be practical on those wooden decks though.

I too thought that dorade vents were directable to scoop air when required or face away from rain or spray?

 

[Refueler]

I'm with Will ..... most vents like that are rotatable depending on boats use at time ...

I have a Solar low profile vent in box .... I have ummed and arred about fitting it ... with people telling me they leak ! It has a blanking plug and ON / OFF switch .... can pull air IN or OUT by swapping the fan blades ...

My latest boat has medium profile static vents .... and they have only had a very rare drip from one ... I mean VERY VERY rare ...

This has caused me to re-think the solar .. as the design is not that much different - other than the Solar is low profile.

 

[wingcommander]

Yes mine do spin through 360 degrees

 

[Dellquay13]

I'm with Will ..... most vents like that are rotatable depending on boats use at time ...

I have a Solar low profile vent in box .... I have ummed and arred about fitting it ... with people telling me they leak ! It has a blanking plug and ON / OFF switch .... can pull air IN or OUT by swapping the fan blades ...

My latest boat has medium profile static vents .... and they have only had a very rare drip from one ... I mean VERY VERY rare ...

This has caused me to re-think the solar .. as the design is not that much different - other than the Solar is low profile.

That’s the type of Solar vents I have always fitted. I’ve found them to be fine in wet West Wales. They haven’t leaked, but cut down the amount of condensation when aboard on cold nights and stop damp or stale smells when the boat is closed up for weeks on end in winter. Obviously not a real winter like you get in the Baltic, just damp maritime Atlantic winter.

 

[Roberto]

Remember also that if air must come in, it must also be able to go out, so arrange your vents in order to have them working both ways (as it seems to be the case in the picture )

 

[Neeves]

it is difficult to be certain but it looks as if your yacht is in marina, or at least tied in a fixed position - why else would you be deploying fenders?

You also have wet decks - maybe it has been raining. Your dorado orientation is any which way but depending on the wind and rain your dorades (or some and at least one of them) will accept rainwater. If you are on board when its raining the dorades can be orientated by hand (so that they are not rain scoops), if you are not on the yacht the dorades need to be plugged - as the wind and rain can then, again, come for any which direction.



Jonathan

 

[B27]

When I use to race harder than I do these days, we sometimes got serious water on deck.
I have one of the common solar vents on my boat, I don't think I'd want it forward of the mast or over my bunk.

In port, some sort of wind scoop over a partially open hatch is good.
A cockpit cover with a washboard out can be good.

And fire up the chinaspacher.

 

[RunAgroundHard]

The Platstimo boxes you have are poor designed dorade boxes which is why they let in water. You could build a custom dorade box around the hole, fit a cowl and have better performance than you have now.

The poor design Plastimo Dorade Boxes - 2 Colours - 2 Sizes
A better design Dorade box - Wikipedia

The difference between the two is the torturous path on the second one that restricts water flow.

My dorade boxes (Rival) were moulded with the coach roof but have the removable cowl on top with a screw in blanking plug for heavy weather. I can take big waves and see no water down below when the blanking plug is not fitted.

I have an older version of this Force 4 Waterproof Ventilite Shut Off Vent which you could fit instead of the Platsimo crap. Mine doe snot have the shut off valve, but an electric fan (land rover wiper motor apparently).

I also get great air flow inwards and outwards, depending on cowl position, as others have suggested. In my view this is an easy fix with no need for solar powered fans. I do have the flat cowl style with clear plastic in the middle and two motor driven and fans. These are in the heads and make a reassuringly loud noise as well as shifting a lot of air.

All the best with your solution.

 

[RunAgroundHard]

Endurance 40
View attachment 164181

Lovely boat by the way, great for cruising and lounging on deck.

 

[mhember]

A dumb question perhaps but aern't those vents meant to be rotated depending on conditions? ie face forward when on anchor providing air into cabin. Face aft when sailing up wind to draw air out of cabin. ol'will

Yeah we rotate the cowls depending on weather, sorry was not clear. It is the base parts which I think are the wrong way around. Ie they have the cowl forward of the deck penetration so rushing water goes in!

 

[mhember]

it is difficult to be certain but it looks as if your yacht is in marina, or at least tied in a fixed position - why else would you be deploying fenders?

You also have wet decks - maybe it has been raining. Your dorado orientation is any which way but depending on the wind and rain your dorades (or some and at least one of them) will accept rainwater. If you are on board when its raining the dorades can be orientated by hand (so that they are not rain scoops), if you are not on the yacht the dorades need to be plugged - as the wind and rain can then, again, come for any which direction.



Jonathan

Hi this is an old picture. They don't leak from rain, it is when we dig the bows into a decent sea and water runs on deck.... trying to find a vent that can cope with that/ be easily closed as well as move a bit more air. I might be asking for the impossible!

 

[mhember]

The Platstimo boxes you have are poor designed dorade boxes which is why they let in water. You could build a custom dorade box around the hole, fit a cowl and have better performance than you have now.

The poor design Plastimo Dorade Boxes - 2 Colours - 2 Sizes
A better design Dorade box - Wikipedia

The difference between the two is the torturous path on the second one that restricts water flow.

My dorade boxes (Rival) were moulded with the coach roof but have the removable cowl on top with a screw in blanking plug for heavy weather. I can take big waves and see no water down below when the blanking plug is not fitted.

I have an older version of this Force 4 Waterproof Ventilite Shut Off Vent which you could fit instead of the Platsimo crap. Mine doe snot have the shut off valve, but an electric fan (land rover wiper motor apparently).

I also get great air flow inwards and outwards, depending on cowl position, as others have suggested. In my view this is an easy fix with no need for solar powered fans. I do have the flat cowl style with clear plastic in the middle and two motor driven and fans. These are in the heads and make a reassuringly loud noise as well as shifting a lot of air.

All the best with your solution.

Thanks I think the force 4 vent might be the way ahead, also the same size hole so less disruptive to fit. Also agree that the Plastimo dorade boxes are not well designed, I think the narrower part should face forward, but even so the limber holes are all the way around which means water running aft on the deck runs in and bounces over the small upstand.

 

[KevinV]

Those white plastic dorade boxes do look horrid on that lovely deck - they're quite a simple thing to make in wood. I can see that across such a flat, clear deck the water might get some speed up, so a slightly taller than usual design might be called for.

FWIW in my limited experience the cowls are pretty useless as scoops (ie facing towards the wind), much more effective working the other way round (like the needle in carb) - but you don't get a noticeable breeze.

 

[srm]

Suggest you look at the original design of Dorade vent boxes by Sparkman and Stevens. They were much bigger than your toy Plastimo variety and they worked without fans.

Basic physics, the smaller the hole the greater the friction/resistance to air flow. Lower profile on the weather deck means greater chance of water flowing below and less air speed over the vent. As you have seen there are times you have a significant depth of water continuously flowing over that deck.

Given the design of your boat I would echo @KevinV and make nice wood boxes of sufficient volume with correctly positioned baffles and drains plus tall cowls of at least 6 inch (150mm) diameter that can be rotated and a slightly larger through deck vent. If worried about ropes snagging that can be solved by a ss rail curving over the cowl, and also provide a secure hand hold on that big exposed deck.

When I made mine the through deck vent was a length of plastic drain pipe epoxied through the deck flush with the head lining and extended upwards in to the box to make the second baffle. These were also on the weather deck and did not let water below. The top of the box was removable and could be reversed to place the cowl directly over the through deck vent to improve ventilation when anchored in dry climates.

 

[Refueler]

It is evident when you look at old worlde boats - that Dorades were often mounted on top of plinths for the very reason given by others.

They were not just the dorade and its own 'box' .. there was a wooden box THEN the dorade.

Many if I recall correctly had the actual dorade upper vent pipe at the aft end of the 'box' - with the actual raised vent pipe to cabin in the fwd half.

 

[doraymefa]

I thought the design these vents is to suck air out, pressure less in fast flowing fluid…
The air therefore comes in elsewhere, perhaps an open but protected saloon entrance hatch.

 

[RunAgroundHard]

I thought the design these vents is to suck air out, pressure less in fast flowing fluid…
The air therefore comes in elsewhere, perhaps an open but protected saloon entrance hatch.

They do both depending on orientation and of course shape of cowling and other openings in the hull.

 

[srm]

It is evident when you look at old worlde boats - that Dorades were often mounted on top of plinths for the very reason given by others.

They were not just the dorade and its own 'box' .. there was a wooden box THEN the dorade.

Many if I recall correctly had the actual dorade upper vent pipe at the aft end of the 'box' - with the actual raised vent pipe to cabin in the fwd half.

The wooden box is a water trap, as designed for the S&S yacht "Dorade" by Rod Stephens. Cowl brings air and water in at one end, air enters cabin from other end of box via the vent pipe. A pair of baffles, often extensions of the two vents, ensures water falls to the bottom of the box and only air goes into the cabin. Water then drains out through holes at deck level, usually aft. Very simple and effective provided that the vents are large enough to give a free flow of air and the baffles are high enough to prevent water overtopping (as happens in so many small commercially available mouldings). Walking around our marina this afternoon, located where a few ocean crossing yachts stop each winter, I noticed only two boats with sensible sized Dorade ventilators.
Simple diagram here: Dorade box - Wikipedia

Ventilators of any design mounted on the weather deck, as opposed to cabin top, are more vulnerable to overtopping of baffles due to the amount and depth of water that runs across the deck. Mounting them on a block, even 2 inches (50mm) or so high can reduce the quantity of water entering. As I discovered when raising an anchor winch with down pipe that led to below waterline chain stowage that drained to the bilge.