Hi all, I'm a newbie to this forum and to self fit outs and wonder if some of you on this forum could offer some advice.
We've just had a 58' trad stern shell built, complete with a steel enclosed cratch. The boat will have a Beta engine at the rear, under the rear entrance hatch. We've got 7 x 4" mushroom vents in the roof of the shell so that each compartment has at least one mushroom vent so high level ventilation is adequately covered to meet requirements of the BSS examination.
Using the formula in the BSS guide, we need 1300 mm^2 ventilation area for the bedroom, 650 mm^2 for the bathroom, 19300 mm^2 for the saloon / galley and 8340 mm^2 for the rear cabin.
At the rear of the boat, we can fit vents at the bottom of the doors into the cabin space and vents in the sides of the rear bulkhead ducted down to the bilges / engine bay to satisfy the need for low level ventilation, however we don't currently have any facility for low level ventilation at the front of the cabin area due to the enclosed nature of the steel cratch. If we had a well deck we could fit vents in the front doors or to the sides of them but this is not possible due to the design of the boat (to maximise use of internal space as it is intended to be a liveaboard)
We've probably got just enough mushroom vents to duct 2 of them down to low level but that would be approx 15 feet from the front of the cabin space so not ideal. Would a better option be to have vents cut into the beam across under the cratch triangle and duct down to low level?
If we were to do that, we could duct one vent down into the bilges to promote airflow through the bilges but is it best to vent this seperately from the engine bay to prevent the engine from drawing in potentially damp air or is that unlikely to be a problem for the engine?
Sorry about the Tolstoyesque nature of the post but it's probably best to give you the best idea possible.
Cheers,
Pete.