Side-opening main hatches on a cat- good or bad?

[rayaldridge]

I've changed my mind again, for about the thousandth time. For a while there I was planning to have little footwells behind the cabins for helmsman comfort, but I eventually decided I couldn't give up the interior volume under the footwells.

Lastest drawing:



Unfortunately, this means that the main companionway hatches must open onto the center deck. My opinion is that hatches located on an aft-facing bulkhead are drier. Our old Wharram Tane had hatches that opened onto the center deck, and in heavy weather, the lee hatch would let spray through.

So how bad a problem is this? Other problems with side hatches? Best ways of insuring that these hatches are as tight as possible?

Any help will be appreciated.

[Howaya]

Several years ago I met a fellow who was building a Woods Romany. He mentioned the hatches to the hulls let rain in if the near-vertical wash boards weren't in place. We came to the conclusion there were a number of solutions but one in particular was easiest to implement: a sliding or hinged brow.

[rayaldridge]

Could you elaborate?

[Richard Woods]

My original 24ft Strider catamaran has aft facing hatches. The later Strider Club has sliding side hatches

I have owned and extensively sailed both versions

The aft hatch allows you to store long things, like dinghy masts etc in the hulls. And it is easy to reach into the hull while steering

The side hatch helps divide the accommodation up better and makes the hull less of a tunnel

I have just been sailing on a Saturn with side hatches. Andrew Slow is a superb boatbuilder. He said it took way to long to make the first sliding hatch, so his second hull has a simple lifting hatch.

The advantage of the sliding hatch is that you can half close it, so he has the galley in that hull.

You can always fit an aft hatch on one hull and a side hatch on the other.

I don't think you need worry too much about spray coming on board. I'm sure you have much more freeboard than a Wharram and a drier deck area. Certainly I never had any spray problems on my Strider club during my sail from the UK to the USSR

Don't worry about the fact that you are changing the design. Everyone does that, just most keep it secret

As you will have learnt by now, you throw away about 4 designs for every one you keep

Richard Woods of Woods Designs

www.sailingcatamarans.com

[thedutchtouch]

forgive me if it's a silly suggestion but why not just do both? more access seems better to me? or am i violating the KISS principle?

[Petros]

Having both would add weight and cost, and twice the opportunity for things to break. I suspect the side hatch would weaken the hull structure, which means you have to reinforce the hull more than you would with an aft hatch. That depends on the hull design of course.

[Alex.A]

What works best for the interior - why the change of plan ? wharram builders and friends has some discussions on hatches - improvements on....
As a cruiser you want an interior. Especially a small cruiser.
Over thinking is good.......

[rayaldridge]

Richard, thanks for the encouragement. I caught a lot of hell from self-proclaimed experts when I was building Slider, because I wouldn't make up my mind until I absolutely had to... but it turns out that was a good thing. When I built my little cartop cat, I was convinced I knew what I was doing, so I just blasted through the build, clinging to all my assumptions about the design. It was a disaster, and it took me a year's worth of modifications before the little cartopper became a sweet boat. And if I were building it again, I'd change even more stuff.

I think you're right about the boat being a lot drier than our old Wharram. Much more freeboard, and solid center decks instead of the cedar slat decks we had (and have on Slider, too.) Plus, the beams are quite tall, compared to the Tane beams, which were just a couple of 2X4s glued together. I loved that old boat, but the design of the beam connections was the worst, the absolute WORST. The doubled 2X4 beams lay in plywood troughs that trapped moisture, and the beams and boxes rotted away faster than I could keep them fixed. Terrible. But anyway, wind-driven rain is a concern, as well as spray. I hate being damp at sea.

Which side of the lifting hatch did Andrew Slow put his hinges on? I've been scratching my head over this. The most sensible approach would seem to be to put the hinges on the forward edge of the hatch, and provide a way to tie it open so it isn't likely to blow shut and mash fingers. If you hinge it on the side opposite the drop boards, then when it's open, I worry that it would stick out past the outer cabin sides and snag sheets. If you hinge it on the aft side, I worry that it might blow open when shut but not latched, or that it might be more vulnerable to sweeping seas (which I hope never to see, but you never know.)

[rayaldridge]

Originally Posted by thedutchtouch

forgive me if it's a silly suggestion but why not just do both? more access seems better to me? or am i violating the KISS principle?

The reason I can't have hatches aft is that's where the galley and nav station will be, and there'd be no way to get through those structures to the open part of the cabin. These hulls are only 44" wide at the gunwales in the widest part of the boat, so there just isn't room for both companionway ladders and the accommodations I want in the aft ends of the cabins.

Before I made the changes, I was envisioning climbing down the shelving that would have formed the minimalist galley in one hull, and storage in the other. Having a proper companionway ladder is another advantage of hatches in mid-cabin.

[DarthCluin]

Since you once owned a Tane, you might appreciate this. A while back I found these pictures of an Australian Tanenui:

[rayaldridge]

Hey, that's slick. Ours was a Tane-oldie, and I think the Tanenui has wider hulls. Ours sure seemed narrower than the pics you posted.

[Corley]

I could not find a good photo of the hatches on the Simpson Formula 1 catamaran they work well though and give good ventilation to the hulls.

[Richard Woods]

Andrew hinged it on the outer side. That way he didn't have to worry about the deck camber interfering with the hinging. Its what I have done as well. When opened it hit the shrouds which stopped it over opening

Richard Woods of Woods Designs

www.sailingcatamarans.com

[rayaldridge]

Thanks, Richard.

Looking at the pics Darth posted, I noticed that the main hatches go most of the way across the top of the cabin. That's a very attractive idea, because then we could stand up to cook, if the weather was good.