Multihull Ventilation?

[gbanker]

In looking at multihull listings (pictures) on the internet I was wondering how the aft cabins get any air at anchor. I currently sleep on a monohull with a large hatch directly over the berth. Much needed and appreciated. Also, while I'm at it, how do you get a breeze in the cockpit with the big wall (deckhouse/cabin) in front of you? Thanks

[44'cruisingcat]

The same way aft cabins on monohulls get air - through hatches. Getting enough breeze in the cockpit is never an issue.

[Sunspot Baby]

Ventilation is sort of "flow through." At anchor the boat heads into the wind. Forward hatches sccop in air which moves through the boat and exits through hatches over our berths. We have some small 12v fans to direct air onto us when in the berth. We have spent some very warm nights on the boat and been comfortable.

George

[schoonerdog]

For our boat we have a large hatch in the aft cabins and smaller hatches both directly behind the birth and another in the adjoining head. The port hull has 12 hatches, starboard 11 and then two hatches over the settee area for a total of 25 opening hatches. Ventilation isn't really a problem. Some catamarans though such as mine and the PDQ 36, amoung others, put their primary larger cabins forward.

[fhrussell]

I've been on a couple of cats that had a hatch on the wing below the settee. Open that up at anchor and feel the windtunnel!.... very comfortable. Catamarans ventilate well with small ventilators at the bows on deck for air movement in the hull.
Also, there is never an issue with ventilation into the cockpit. It seems people prefer the protection of the cabin wall, actually. That's why you see so many cats with the bulkhead mounted console. I prefer dual outboard stations, but to each his own. But at anchor, the bulkhead does provide nice protection. If it does get too hot, bring the party to the front net!

[cat man do]

If it does get too hot, bring the party to the front net!

Good one, we have front deck's big enough for an outdoor gazebo on this cat. As a lot of our cruising is in stinger and crocadile country, we'll also have an inflateable pool up front.

1200 mm wide side deck's should keep the drunk's safe for the trip back to the cockpit.

We'll be having plenty of ventilation through 12 500 x500 hatches that I've made a mould for. Also the front cabin windows 650 x 600 will open, sliding windows around 1200 x 600 in cabin sides for cross ventilation, 12 opening portlights in hull sides, 2 large opening windows in cockpit B/H and some ventilation through the front lockers as well.

Mould's for everything except for the sliders in the side will keep the $$$ and the weight down.

Dave

[northerncat]

dave any sites or info on making molds for making things i still have all my hatches to make and would love to learn the technology?
sean

[cat man do]

Originally Posted by northerncat

dave any sites or info on making molds for making things i still have all my hatches to make and would love to learn the technology?
sean

G'day Sean, no sites as such for me, I just make a female mould from melamine coated Craftwood of what i want, sand it up all pretty and give it a couple of resin coats to seal.

Sand any bumps off and give a few good coats of mould release wax, then a couple of coats of pva release agent.

For the hatches shown I used 400 gsm d/b then 10mm foam as a core and another 400gsm d/b.

The sides had a few extra layers of scrap 400 until it was a couple of mm thick.

Give it a day or two and pop it out.

Same method's used for hatch frames and for deck locker self draining frames and shower stall gutter/ drain thingy.

The pic show's hatches on last boat, the newie will be the same except i'll use a lighter glass and Gabboon core and i'll stick the window on with double sided tape.

The handles are a spare part from Allyacht Spars for the Moonlight hatch

Hope this helps a bit, and have a great holiday

Dave

[northerncat]

dont happen to have any photos of the mold do you i kind of understand what you mean but im pretty good with pictures, thanks heaps for the info and you to have a good christmas, hopefully ill knock over the rest of the structure and exterior painting before the holidays start

sean

[cat man do]

Bloody hell Sean, never let it be said I never gave you a Chrissy present

Pics 1,2,3 are pretty self explanatory.

Pic 4 is a deck locker lid

Pic 5 is the self draining frame that at this stage does'nt drain building dust at all.

Pic 6 is of the mould I made that is pretty much rooted now, but only needed it for 2 of this size frame

Hope this gives you a better idea,

Have a few crays and bellywash for me at Chrissy.

Dave