Hatch Opening Side

[JonathanSail]

I have a question about on-deck hatches, specifically forward hatches on monohull sailboats.

It seems that the natural air flow through a smaller monohull with it's bow in the wind on anchor etc. will be from the companionway forward. I'm guessing that for that reason a lot of older sailboats that I've seen have forward hatches with the hinges on their forward end. This arrangement also seems that it would be a little less vulnerable if left open underway.

My question is, if those observations are true, why are most modern hatches setup with their hinges on the aft end? What are the functional benefits of an aft hinged forward hatch vs. the forward hinged hatches? My guesses are that the aft hinged hatches look better to buyers, or make passing sails through the hatch easier. They also may perform better in terms of ventilation when the companionway is closed?

I don't think that it will be reasonable for me to reverse the setup of my forward hatch on my Pearson 28-1 should there be no benefit from aft-edge hinging but I may add a small hatch above the main cabin at some point and wonder which way it should be oriented (forward/side/aft opening)? In general though I'm curious about this and would like to learn more.

Thanks,

Jonathan

[four winds]

If the bow is facing into the wind, as is normally the case, would not the wind enter the forward hatch and exit through the companionway?

I think it would. I can't recall seeing a boat with the hinges on the forward edge myself, but I'm not the most experienced sailor afloat.

BTW, I use a Breeze Booster that was on the boat when purchased and it works very well.

[Lancerbye]

I guess it might depend on how much you use the forward hatch. I have used mine rarely only when at anchor. Location may also come into play. In this part of the world, it never gets that hot in the forward master state room. I basically see this hatch as an emergency exit. I also have four other opening side ports.

[JoeDiver]

Well, my forward hatch opens so that it can act like an air scoop, hinges on the aft side.....bow facing into the wind at anchor, under motor, or under sail on a long tack. Makes for a nice breeze through the boat, through the cabin and out the companionway.

[sarafina]

We have always used the forward hatch in warm weather or when airing the boats out.

Propped up and the companionway hatch open there is a steady flow of air thru the boat, one way or the other. In dock it depends on how the winds blowing, but at anchor the wind blows into the vberth and out the back thru the cockpit.

And unless it's a cold night we sleep with the hatch over our vberth cracked open for fresh air.

[four winds]

One thing I like about the Breeze Booster, at the dock, it can be rotated through 270 degrees to take advantage of the wind from almost any angle.

http://www.breezebooster.com/

[SabreKai]

Oddly enough my forward hatch has the hinges on the forward edge. I guess the installer figured it would act as a venturi as wind flowed over and past it and suck the warmer air out of the forward hatch and in at the main. I cut a couple of pieces of wedge shaped ply so that the sides are blocked off and the venturi effect is more pronounced.

Sabre

[Weyalan]

Forward pointing forward hatches are great at anchor, but terrible at sea.

[roverhi]

We found that leaving the forward hatch open under way wasn't a good thing. Any spray that came over the bow, and it always seemed to happen, ended up below on our V berths. Suppose if we'd had a hood to put over the hatch so the water couldn't get in from the side, it might have been drier. Never really needed the hatch open while sailing except in the Doldrums. Then it was so flat and no breeze that leaving all the hatches open had little cooling effect.

We made a pup tent like windscoop that tied at the peak to the forestay and down the the lifelines on each side and flat on the cabin top just aft of the forehatch. It shaded the foredeck and acted as a windscoop at anchor. Kept a nice breeze flowing through the boat if there was any wind at anchor.

You are right, the natural airflow, without a windscoop, is aft to forward. It's just not very strong and the boat heats up. Our windscoop made the boat much cooler than just shading the foredeck

[sailingaway221]

Some boats... not all though seem to have a setup that creates a venturi through the hatches... if you open them all or the right ones... Even when the bow is pointing into the wind a backwards facing hatch can be beneficial to the airflow.... If I open the very back port hatch on my boat and not the two backwards facing hatches also .. .....the airflow through the boat is significantly reduced... If I just open the forward facing ones and the back one... I get much less cooling and airflow. Backwards facing hatches probably get ripped off the deck a lot less than forwards facing ones. In any kind of seas at all on most boats you probably want to make sure ALL the hatches are secured closed.

[Hudson Force]

I have hatches on deck that have quick-release pins set in the hinges that can be moved to the forward or the aft side of the hatch; however, I rarely change their orientation. I keep the forward hatches hinged aft and the aft hatches hinged forward for my best air flow below.

[four winds]

Interesting information here for someone new to big boats. My Hobie18 had no hatches.

Wind blowing bow to stern can create air flow inside the cabin flowing forward and out the forward hatch. I'm thinking this requires a rear facing hatch cover to create a venturi effect. But considering the larger opening of the companionway compared to the forward hatch I can see this happening.

I have two forward facing hatches on deck that remain closed while sailing. When appropriate the four openings ports are open for air flow while sailing. Since I'm singlehanding usually, I'm on deck anyway.

[Auspicious]

I have four overhead hatches. Three have hinges at the forward edge and one aft. In the v-berth, the forward hatch on the foredeck is hinged at the forward edge while the after hatch on the cabintop is hinged at the aft edge. The hatch in the main salon and in the aft cabin (center cockpit boat) are hinged at the forward edge.

At anchor with the three forward-hinged hatches open and the breeze over the dodger creates a vacuum in the cockpit that flows down the companionway, through the boat, and out the hatches (and any ports that are open). It is effective. I generally only open the forward facing hatch if I have guests that want to close the door to the v-berth.

Everything is locked down underway so hatch direction isn't relevant.

[Hudson Force]

Originally Posted by Auspicious

................Everything is locked down underway so hatch direction isn't relevant.

Good advice and this last statement is often true, but then we have a lot of easy light air days with some hatches open too.

[mrohr]

HI ALL: it seems air moves from aft to fwd if boat is anchored from bow; anchored from stern :I have experienced a mini gale below with dodger acting as a funnel,then when it begain to rain all got wet up to the fwd berths. Just another reason to avoid stern anchoring,but might try it in force 1 again to see if it increased air flow.
BTW with a hatch opening fwd ,the jib sheets will often foul when tacking.