I don't think there is any reason to think a mono hull would be hotter than a cat. You could make a quasi-scientific argument either way (monos sit deeper in the water
which should act to cool the boat). I also don't think that cats are more open than comparable size mono hulls. Remember a 35 foot cat is comparable to a 45 foot mono or there abouts and typically the mono can carry more weight.
But I hate being hot too. Especially when I am trying to sleep. I also hate the sound of generators running all night and refuse to be one of those guys disturbing a quiet anchorage. So here is what we do, look at Breeze Boosters (Breeze Booster - Breezebooster
) and other similar products. They will direct wind
down the hatch. If you will be at a marina vs. on anchor
or a mooring
, look for one that hangs from a spare halyard
and can be directed towards the wind. But you will find it is almost always better to be swinging on anchor or a mooring
on hot nights. If the wind shifts at night the boat will naturally redirect itself into the wind and you will continue to get the breeze below.
Keep the hatch boards out at night. This will allow for airflow. If you just open the hatch over the berth you will get less airflow and it won't be as effective at cooling
the space. If security
is a concern, you can get bars made up for the hatch and the main companion way. (Atom Voyages - Improving Your Boat's Companionway
) You may also need to look at bug screens depending on where you cruise
Next add some 12 volt fans. We have 4 of the Hella Jet Fans. They are one speed and a little loud (we like the white noise
so that doesn't bother us). We also have one of the Caframo Sirocco 807 Fans. This fan is quiet as long as you keep the blades clean (gets off balance and ticks otherwise). It can move a lot of air and has multiple speeds and a timer built in. Defender Marine
has a really good selection. (Defender.com Search Results: fans
Lastly, and we just began experimenting with this last year so I can't say this is truly affective yet, keep the boat closed during the day with all the shades drawn. The theory here is that you won't heat up the cabin
as much during the day so it won't be as hot below. Seemed to work
pretty good from our limited experimenting with it.
Good luck and fair winds,