"Cooler" Boat

[scarlet]

I have friends who chartered a monohull in the BVI a couple of years ago in the spring, and they said they were so hot at night that they ended up sleeping in the salon and cockpit. (they are monohull people, not multihull)

This year, in the spring, we chartered with them in the BVI, and chartered a small 38' Lagoon catamaran. I was not hot at all, unless I was in the hull whilst sailing with the hatches closed. But, at night, with the hatches open, it made the salon and the hulls wonderfully cool.

So, do you think the temperature could have been that much hotter when they chartered their monohull? OR, are the multihulls just cooler? Now, we slept in the master hull, and had 4 overhead hatches starting in the Head in the bow all the way aft.. also 3 sidelights all open.. and 2 of those tiny fans...

We have friends that have a Hylas 48' Center cockpit.. and I have to imagine the ventilation in the aft cabin must be horrible... but, I don't know.

Anyone have any experience with this?

[44'cruisingcat]

With the big deck areas, there's certainly the opportunity to ventilate cat's well.

How well it's done will depend on the builder.

[barnakiel]

Your thermal comfort will depend i.a. on season, year, location, boat design (sandwich is cooler than non insulated solid grp, etc.) anchorage, wind force, your fitness level, your genetic factors, your sex ...

Etc.

There are just very many factors.

Cheers,
b.

[JPA Cate]

Hi, scarlet,

It's not really a mono vs cat sort of deal. What comfort does depend on in really hot, humid areas is 12 v. fans to dry one's perspiration. The assist to the normal air circulation is critical, as the sweat dries, you cool enough to sleep. The closest to the equator we've been is the Solomon Is., and the fans worked fine there; eventually, one acclimates, too. We found ourselves feeling cool at 23 deg. S. summer, after that trip.

I can remember being in the Sea of Cortez, and it being so hot, we'd swim to cool down, around 9 p.m., then go to sleep, and a few nights I went outside and slept on the sail bag. It does take time to acclimatize when it's lots hotter than one is used to....at a rough guess, about 6 weeks.

Ann

[Catmandu]

My experience is that on the hook two things make a huge difference:

1.) Insulation in the coachroof, decks and topsides

2.) Good airflow - fans can do help but many times were not sufficient.

So a boat design that can funnel air through the boat while on the hook (even during rain) without letting bugs in works best.

[sck5]

If you are at anchor rig tarps to shade the deck. Makes a huge difference.

[Island Time O25]

+1 for deck shade during the day when there is no wind. With wind there should not be a big problem in well designed i.e. well ventilated boat.

[Cheechako]

It's just hard to say. Cat or mono , if there is a hatch directly over you it will help a lot. If not it's terrible. That's what I hated about my boat with a Pullman berth. There was a very small hatch over, maybe 12 x 12 and it was stuffy a lot.
However, there are just certain weather times when it's stuffy and hot... regardless of what you are in.

[sailjumanji]

Originally Posted by Catmandu

My experience is that on the hook two things make a huge difference:

1.) Insulation in the coachroof, decks and topsides

2.) Good airflow - fans can do help but many times were not sufficient.

So a boat design that can funnel air through the boat while on the hook (even during rain) without letting bugs in works best.

This (above). Exactly.

[Cheechako]

Originally Posted by Catmandu

My experience is that on the hook two things make a huge difference:

1.) Insulation in the coachroof, decks and topsides

2.) Good airflow - fans can do help but many times were not sufficient.

So a boat design that can funnel air through the boat while on the hook (even during rain) without letting bugs in works best.

Yep Those nylon "windscoop's" are amazing on a bow hatch with an aft hatch open. Like a gale in the boat sometimes! The best one I had didnt need a lifting halyard though, it had a fiberglass rod like a tent rod that made it a 'conestoga" shaped scoop.

[jdazey]

Originally Posted by Cheechako

Yep Those nylon "windscoop's" are amazing on a bow hatch with an aft hatch open. Like a gale in the boat sometimes! The best one I had didnt need a lifting halyard though, it had a fiberglass rod like a tent rod that made it a 'conestoga" shaped scoop.

+3 on tarps and awnings.


Those particular wind scoops can be a challenge to rig on a catamaran but the idea is sound. All the other advice matches our experience.


Cheers,

[thinwater]

Aft cabins can be tough to ventilate.

[mikereed100]

A trick we use on our cat at night is to open all the forward facing hatches and the forward cockpit door, while closing all the back windows and aft facing hatches, leaving only the aft facing hatch above our bunk open. This creates a bit of high pressure within the boat with the only outlet being the hatch above our bunk. It actually works pretty well and allows us to sleep without a fan on in the tropics.

[scarlet]

Originally Posted by Catmandu

My experience is that on the hook two things make a huge difference:

1.) Insulation in the coachroof, decks and topsides

Is that easy to do? I'm thinking you would have to dismantle the entire roof and sides. Or, can you use some of that "blow in" insulation?

[scarlet]

Originally Posted by sck5

If you are at anchor rig tarps to shade the deck. Makes a huge difference.

I have heard this. Not only does it shade the deck, but it also creates a small "low pressure zone", which would further cool it.