Are hatch lid vents useful?

[Indolent58]

One of our recent guests stepped on the v-berth main hatch and cracked it. It’s. Lewmar 44 with the round waterproof vent in the center. It’s never been clear to me that these vents are useful - so little air seems to get through - but I could be wrong. The question I’m facing is whether to get a replacement acrylic with or without the vent with the one without obviously being cheaper. The vent doesn’t seem to do much to increase comfort but maybe it plays a meaningful role in controlling humidity and mold? I don’t know so I’m asking.

[coopec43]

Originally Posted by Indolent58

One of our recent guests stepped on the v-berth main hatch and cracked it. It’s. Lewmar 44 with the round waterproof vent in the center. It’s never been clear to me that these vents are useful - so little air seems to get through - but I could be wrong. The question I’m facing is whether to get a replacement acrylic with or without the vent with the one without obviously being cheaper. The vent doesn’t seem to do much to increase comfort but maybe it plays a meaningful role in controlling humidity and mold? I don’t know so I’m asking.

Like you I don't it has much purpose. I definitely wouldn't replace it. If you had a problem with air circulation maybe you could install a Dorade vent?

[JBP]

They do not move enough air to keep you comfy, but they do move enough air to keep a closed up, unoccupied boat from getting too musty smelling. Unfortunately the quality of the ones currently available seems to be be poor. A lot of people have been complaining that the motor in the new ones doesn't last long at all.

[Indolent58]

Originally Posted by JBP

They do not move enough air to keep you comfy, but they do move enough air to keep a closed up, unoccupied boat from getting too musty smelling. Unfortunately the quality of the ones currently available seems to be be poor. A lot of people have been complaining that the motor in the new ones doesn't last long at all.

The vents supplied with Lewmar hatches are passive, not solar powered.

[rwidman]

A hatch vent (or any other vent) cannot move air in or out of a boat unless there is another opening the same size or larger. For example, a vent cannot exhaust air from a boat unless there is another opening to let air in to make up for the air being expelled.

I had a solar vent in my boat next to a hatch, but it did pretty much nothing so when it failed, I plugged the hole.

If you want ventilation, open the hatch a bit.

[capt jgw]

The big hole in the acrylic lens weakens it, it's probably why it broke in the first place. I've had a couple without the vent and stood on them occasionally. They didn't break. Also if the vent can be removed from the outside it makes it easy to break into the boat, just pop the vent out and reach inside to unlock the hatch. I wouldn't replace the hatch vent but might put in another one somewhere else.

[JBP]

Originally Posted by Indolent58

The vents supplied with Lewmar hatches are passive, not solar powered.

Really? That's seems silly. I guess mine is a PO refit.

[Kettlewell]

I wouldn't replace it. For one thing, in my experience they are not waterproof enough when taking green water over the deck or during a hurricane.

[GordMay]

I don’t know what Lewmar uses, but [for instance] Nicro’s “Air Vent 500" is a passive wind-powered vent, that moves about 600- 1000 cfm of air, with a 15-knot breeze.
Over-all 7" diameter x 1-3/4" high, fits a 3-3/4" diameter hole.
They retail for ± $30.

Installing the AirVent 500 ➥ https://ca.binnacle.com/pdf/Marinco%...n%20Manual.pdf