Scott wrote:

Thank you David, Mark and David.

I very much appreciate the advice of long-time sailors. I will take it to heart.

I am shopping for a small ventilation hatch that will go on the foredeck somewhere. I think I will hold on to the full size hatch and use it to make a more water-tight companionway, if I ever have time!

I had hoped to avoid spending money on a new hatch. If anyone knows someone who wants to buy the original mast and other spars please send them my way! That would really help my boat budget.

Proper deck hatches are very expensive, which is one thing that did motivate my decision. But I am happy with my smaller Vetus hatch which measures about 280 mm x 150 mm. The hinges will be on the forward side so the hatch will open on the aft side. That way even in heavy rain it can be left slightly open to provide some ventilation. It is positioned above the head end of the double berth so as to provide ventilation through the night.

The aft cabin bulkhead also has a window which is hinged at the top and can be propped open. This is important for ventilation in New Zealand's quite hot summer climate. 

I am not totally sure of the best answer for a water-tight companionway on a small yacht. Annie has her own very good solution. On 'Footprints' we had a conventional companionway and sliding hatch, with a solid dodger built just around the hatch opening. That proved to be very waterproof even in an ocean crossing environment with waves sweeping across the deck and through the cockpit. But the companionway opening was set forward by about 300 mm from the aft cabin bulkhead which I expect contributed to the success of the arrangement. I had hope to duplicate this on the catamaran but have been unable to do so for practical reasons in such a small boat. So I have a conventional sliding hatch with drop boards in the opening. I intend having a boom tent which I hope will help with a waterproof cabin opening when staying on board during inclement weather. Anyway we are very close to a launch date so will know how it all works out in a months time.

Perhaps Benefits of a fore hatch needs a separate thread?

one other:

the mast falls down, an blocks the main hatch.  A reason to avoid a single outward opening hatch.  You don’t see this on yachts, but all Navy vessel do so.

Scott wrote:

Hi David,

Thank you for taking the time to respond. I think I want more than one way to get out of the boat just in case the main hatch is blocked by a fire in the cockpit or some other very unexpected event. Maybe this is nonsense. Either way I will definitely add some type of dorade ventilators when time and my budget allows.

Scott.

I thought about this on the 6 meter catamaran I am building. I had originally intended to put a full size hatch in the cabin top forward thinking second means of egress in the case of fire. But then I realised on a 6 meter boat I am only a brief second from the main hatch any way, no matter where I am in the interior of the boat. So in the end I have fitted only a small ventilation hatch which allows both light and air into the cabin.

I have also provided for as much ventilation as I can making vents into the open coaming lockers for the aft section of each hull, and vents forward in each hull. The composting toilet will have a small 12 volt extractor fan running continuously which also helps in providing positive ventilation.

I'm not convinced that a small JR boat should have a full-sized forehatch.

There is a need for all-weather ventilation, best provided by a cowl+dorade, eg Air Only.

In hot dry weather, a minimal size (20cm square) ventilation hatch can be useful to get a through airflow.

Neither of these options would unduly weaken the deck. 

Arne:

Scott,
Maybe it's an idea to have a look at the dimensions of my Frøken Sørensen.  The dimensions of those boats are very similar.
Check this: 

https://bit.ly/3jBkOdY

Arne

Arne,

I read through the document you linked. I think I have read through this, and everything you have made public, a few times. It is all gold. Thank you for everything you contribute to the JRA.

At this point I am committed to at least trying to sail with the batten materials I have already purchased. I hope between the AL tube and the bendy fiberglass for short extensions I have what I need.

Reading about the recent capsize of Frøken Sørensen makes me a little nervous about the comparison.