Passive ventilation

[bowball]

With every summer warmer than the previous one, what are creative ideas for passive ventilation and has anyone tried these?

1. Some sort of forward hatch mounted electric fan? Is there any good implementation thoughts?

2. A wind scoop for a forward hatch? How to rig?

3. I’ve seen a fabric “awning” here mounted to keep the sun off the forward berth but still allowing some ventilation, though at the cost of not being able to walk to check on the anchor. Not exactly a ventilation thought though unlike above.

Which is the best combination of most effective and easiest to use of the ideas? Photos?

 

[dhays]

I have been considering a triangular sun sail from the PH roof forward over the bow to shade the forward cabin. I have yet to come up with a low impact, affordable option, but I'm thinking.

I've also considered a scoop over the forward hatch above the forward cabin. However, typically around here, when the weather is hot, there is no wind. If there is wind, it is light and the ever present tidal current is more critical to boat position than any Beaufort 1 or 2 breeze.

Some of the new, cheap, rechargeable fans may be a good option.

 

[bowball]

I have been considering a triangular sun sail from the PH roof forward over the bow to shade the forward cabin. I have yet to come up with a low impact, affordable option, but I'm thinking.

I've also considered a scoop over the forward hatch above the forward cabin. However, typically around here, when the weather is hot, there is no wind. If there is wind, it is light and the ever present tidal current is more critical to boat position than any Beaufort 1 or 2 breeze.

Some of the new, cheap, rechargeable fans may be a good option.

Do you have a Portuguese bridge on your trawler?? Can you run the shade from there to the bow so only a few feet off the deck instead of the pilot house roof?

As for the wind scoop I agree on the breeze but they also make them four sided so the boat doesn’t need to point into the wind.

 

[Comodave]

We use 18/120 hybrid fans. I use Ridgid rans with 18 volt batteries. The fans are extremely quiet and move a lot of air. On low the fans run about 2 days on a battery. They have a lifetime warranty if you register them online within 90 days of purchase.

 

[bowball]

The question on the fans, which I have, is isn’t it better to pull on air from the outside? Hence the scoop or a fan mounted in the hatch opening?

 

[SteveK]

We added Phiterex sunscreen to the pilot house windshield and that made a noticeable difference, already had them on port and SB. On the last heat wave I opened the forward hatches, which face into the wind and that with all doors open kept the boat cool.

 

[luna]

With respect to keeping the boat cooler, provided that you have adequately sized air entry and exit locations I don't think it really matters if you push the air in by way of a hatch mounted fan or pull the air out by way of a fan at the cockpit door. The goal is to move the air through the boat quickly and both work equally well.

If you are trying to keep yourself cooler, you are best served by being in the airstream close to a large fan as what mostly cools you is the evaporation of the moisture on your skin, which is enhanced by the windstorm.

Understanding this, we place fans in places along the length of the air's route through the boat that are also convenient to sit in the fan's airstream.

 

[Comodave]

As I posted above, we use large battery powered fans. We carry 2 aboard so we each have a dedicated fan. We like them better than mounted fans because we can carry the battery fans around to wherever we happen to be so we get optimal air movement on us.

 

[rslifkin]

I'm interested in this one. Our boat ventilates pretty well with even a light breeze at anchor or at a dock provided the breeze isn't directly behind us. But the aft cabin doesn't ventilate as well as the rest of the boat (side windows only and they're smaller than the ones in the salon).

The big challenge for us is in the rain. We lose use of the forward hatch and all of the side windows in rain (side windows aren't quite vertical and will get water dripping through them). So then we're down to the forward portholes (angled down enough to stay dry) and the companionway (which has to be closed if it gets buggy as there's no screen for it).

Fans definitely help in any situation, especially for sleeping. We tend to sleep with one blowing across our bunk (aimed to not hit our faces much).

 

[Hippocampus]

They make windscoops for your forward hatch. They even make them that don’t allow rain in and can handle a fresh breeze. Do that and keep your companionway door open. Done.

One of my major disappointments with all the trawlers we shopped before buying the NT was the absence of effective passive ventilation c/w prior sailboats especially the Outbound. That boat had multiple dorades appropriately placed so that even with moderate green water coming over the decks the interior was dry and ventilation excellent. That meant no mold and cooler temperatures even in the tropics. To the degree we very rarely needed to put the AC on. The exception was when in a marina. Unfortunately there there is usually little wind so AC was necessary. But at anchor or underway with good dorades AC wasn’t necessary in the tropics.
The other exception was summer in the Chesapeake. No wind and bugs when anchoring in all the little creeks. Needed to fabricate a bug screen for the companionway.
Current boat has fans everywhere. They are quiet and low draw. Have bug screens for the pilot house doors. So leave those and the companionway door open and it serves well enough with a fan or three on.