Ventilation hatch orientation

[TomSR]

My sailboat needs more cabin ventilation, so I'm considering adding a 9"x9" Vetus Planus hatch in the cabintop. It would be located about where the cardboard pattern is.


I have seen boats with the hinge line aft, and also boats with the hinge line forward. I can see an advantage for improved airflow when hinged aft, but can also see less spray coming aboard when slightly opened if hinged forward.


Which hinge orientation would be best?

[JPA Cate]

We have always had our boats in temperate zones, and based on that, when you most need the ventilation below decks is when you're at anchor. So, to me aft hinges is the way to go. Or, fans used creatively. Noelex 77 has some very interesting concepts he shares in the "I hate Caframo" or "Caframo is Trash" thread.

You might want to consider making or having made a dorade concept hatch dodger, if you want to be able to leave the hatch open some in the rain. [I have seen a baby carriage pram hood used for the purpose, too. But we made ours for our forehatch. Ours is pretty good, but still have to close the hatch over 20 kn.]

Ann

[kapnd]

I need to install hatches too, and have come to the conclusion that they should be oriented towards the wind in your most usual parking situation.
I’m going to fiberglass in 1 1/2” curbs to mount them on, at least the deck-hatch joint won’t be exposed to the runoff water.
Make sure it’s not mounted directly over the bunks.
A wise man told me that he never met a hatch that didn’t leak at some point in time!

[TomSR]

Originally Posted by JPA Cate

We have always had our boats in temperate zones, and based on that, when you most need the ventilation below decks is when you're at anchor. So, to me aft hinges is the way to go. Or, fans used creatively. Noelex 77 has some very interesting concepts he shares in the "I hate Caframo" or "Caframo is Trash" thread.

You might want to consider making or having made a dorade concept hatch dodger, if you want to be able to leave the hatch open some in the rain. [I have seen a baby carriage pram hood used for the purpose, too. But we made ours for our forehatch. Ours is pretty good, but still have to close the hatch over 20 kn.]

Ann

Yes, I'm mostly concerned about interior temp at anchor. I'm trying to avoid fans, in the hope that passive ventilation will be adequate here in Puget Sound.


The idea of a hatch dodger for rainy weather is interesting, we have plenty of rain here. Some sort of collapsible framework with a fabric cover might be suitable and stow in a minimum of space.

[JPA Cate]

I made ours from Stamoid (my first project with it, a 10 yr. guarantee pvc fabric, with just about zero stretch, and used old mainsail battens for the spreaders needed). It's really useful when it is raining, but you still want to have fresh air coming through the boat.

Ann

[TomSR]

Originally Posted by kapnd

I need to install hatches too, and have come to the conclusion that they should be oriented towards the wind in your most usual parking situation.
I’m going to fiberglass in 1 1/2” curbs to mount them on, at least the deck-hatch joint won’t be exposed to the runoff water.
Make sure it’s not mounted directly over the bunks.
A wise man told me that he never met a hatch that didn’t leak at some point in time!

And that brings up a fear of mine, leaks onto my berth. My previous boat (a 1935 gaff ketch) had two deck leaks; one into the galley sink (the PERFECT leak!), and the other onto my berth (the WORST possible leak).


Working within the constraints of the companionway sliding hatch, the solar panel, and the forward buoyancy compartment, the only suitable place is over the v-berth. Would I regret putting this hatch over my bunk?

[Chotu]

these are the hatches I selected for my boat as well.

I have no leaks. Quite satisfied with them.

I believe they are at least five years now on my boat.

tell me if you find the trim rings or screens.

Originally Posted by TomSR

And that brings up a fear of mine, leaks onto my berth. My previous boat (a 1935 gaff ketch) had two deck leaks; one into the galley sink (the PERFECT leak!), and the other onto my berth (the WORST possible leak).


Working within the constraints of the companionway sliding hatch, the solar panel, and the forward buoyancy compartment, the only suitable place is over the v-berth. Would I regret putting this hatch over my bunk?

[TomSR]

Originally Posted by Chotu

these are the hatches I selected for my boat as well.

I have no leaks. Quite satisfied with them.

I believe they are at least five years now on my boat.

tell me if you find the trim rings or screens.

I'm happy to hear that they are working well for you.
Fisheries Supply has counter-flanges and screens available for some sizes, but not all, of the Planus series hatches.
https://www.fisheriessupply.com/vetu...screens/cf4532

[barnakiel]

What is the scenario ?


Some docks are located so that there is a dominant wind direction thru a year.


Otherwise, some people anchor and some do so with anchor from the bow. Then they may like to have the front (bow) part of the hatch lifting. To 'push the air' into the cabin.


Our fore hatch opens like this. It is effective when anchored bow to the wind.


ymmv


barnakiel

[TomSR]

Originally Posted by barnakiel

What is the scenario ?


Some docks are located so that there is a dominant wind direction thru a year.


Otherwise, some people anchor and some do so with anchor from the bow. Then they may like to have the front (bow) part of the hatch lifting. To 'push the air' into the cabin.


Our fore hatch opens like this. It is effective when anchored bow to the wind.



ymbarnakiel

I try to avoid marinas, almost always anchor out with the mizzen left up so I'm usually head to wind. Sounds like hinge axis aft is the way to go.

[Chotu]

Originally Posted by TomSR

I'm happy to hear that they are working well for you.
Fisheries Supply has counter-flanges and screens available for some sizes, but not all, of the Planus series hatches.
https://www.fisheriessupply.com/vetu...screens/cf4532

Thanks!! those are hard to track down

[barnakiel]

Originally Posted by TomSR

I try to avoid marinas, almost always anchor out with the mizzen left up so I'm usually head to wind. Sounds like hinge axis aft is the way to go.

For, me, then this would be opening forward (hinges aft). This is too how my boat has it. I am happy with how this works too. We too anchor with bow anchor - head into the wind, when there is any.


I am sure I have seen at least one hatch opening both ways. Not sure which brand it was though.


b.

[Island Time O25]

I have the original Bomar hatches from 1980. Both large ones have reversible hinges. I dont think I ever had the hinges forward as I dog them when sailing. My 4 dorado vents are enough to provide enough air circulation while moving. Plus seldom is anyone in the cabin while we sail. And one of the dorados is venting the head. There is a small 8x8" hatch over the galley which has a forward hinge but is is mostly closed as it is next to the sliding entry hatch.

[TomSR]

I installed the Vetus Planus hatch with the hinge aft, and the breeze at anchor was a great improvement this summer.

As Chotu mentioned, they don't leak a drop. And they are very affordable.

An unexpected bonus of installing the hatch over the berth is that I can check for wind strength without even sitting up...

[rognvald]

Forward hatches are an elementary necessity for a cruising(non-marina) sailor where max air flow can be maintained. Also, passive ventilation throughout your vessel makes a healthy boat with stainless vents/1/2" holes in critical living/storage areas. The only time we've ever had mildew(very minimal) was during long-term dry storage.
Rognvald