33-2 Ventilation Strategies

Update

Pretty pleased with these improvements overall, and I think that I would make ventilation a priority on a next boat, and resolve any issues sooner.  (I waited several years to deal with this on Windstar.)

The Nicro day and night vent seems to stop, then start again if I cycle the switch. Not sure if that's a result of a reset mode when discharged or not.   Also, I have read several posts from owners who are repairing these things when the motors fail, and are using a similar motor used in 12v toys, and available inexpensively on Amazon.   My next boat wont have one of these.  While I like the principle, it seems a lot like an expensive toy, and for me at least, one of the pleasures of sailing is knowing that the boat is tough and simple, and that modifications and upgrades are well-reasoned and soundly engineered.  I think a few rugged, heavily built passive vents are the way to go.   Oh well.

The 33-2 needs better ventilation...

As on most production boats.

The 33-2 was designed without any consideration of ventilation or air movement (other than opening its hatches).   This is not ideal, and I decided to start with two approaches.
  

Adding a V-Berth Dorade Vent

First improvement was to copy a feature of the CS36T; the use of  the anchor locker as a dorade box.   This is done by installing a cowl vent in its hatch, and cutting vent openings in the bulkhead at the foot of the v-berth.

I used a nicro/marinco 3" low-profile cowl vent and its associated hardware for both the deck hatch and vent trim, as this would standardize on snap-in closure plates. 

A hole saw was used to cut all 3 holes.   As the cowl vent is not an overly stressed area, (and I'm a bit lazy) I did not remove the balsa core from the hatch lid, instead taking care to drill the holes oversized, epoxy all exposed surfaces, and to tighten the nuts and screws carefully so as not to crush the core.    I used butyl tape to carefully seal the plate to the deck to further protect the core.  The cut edges of the interior bulkhead were also coated with epoxy should they ever encounter water.

The approach works and there is improved air movement as a result.

Adding a Day and Night Solar vent.

The second step to increasing air movement was to add a day/night solar vent.  (a gadget I’m not quite sold on.)  

Choosing a location is a challenge on the 33-2 as these vents are quite bulky and have the potential to snag lines, plus the deck is quite cambered in most areas, making installation impossible without building and fitting a base. I had considered adding this to the fore-hatch however even the smaller sized vent is quite high in profile, and I was warned that the slope in the hatch might contribute to leaks.  Furthermore, many of the passive vents available have closure mechanisms that protrude into the cabin, and would in my view have been unsightly on the inside hatch, as well as providing yet another place to bash my head.

I elected to install the vent on the centerline of the coach roof, forward of the opening hatch, with the interior trim penetrating through what had been a frosted acrylic lens for a fluorescent fixture, which needed replacement.   This was much preferred to cutting a hole in both the deck and the liner and the lens modifications were combined with a much-needed lighting upgrade.   There is just enough space here to install the 3” unit on the flat of the deck, though I drilled for a 4” should I later decide to install one.   (it will overhang at the forward edge slightly) 

Installation was straightforward, and I was pleased to see that the deck is cored with quality marine ply in this area.  

As usual, holes were drilled oversize, epoxy was used to seal the core, butyl tape to seal the fitting, and machine screws/nuts were used instead of wood screws.

The lighting is an improvement though these fixtures are too bright when relaxing below, and I have acquired a dimmer to address this.   The advantage of course is that since the existing plexiglass lens was used and the liner was not drilled or modified, the lighting can be changed at any time by making a new plexiglass panel.  3w LED fixtures are from Amazon.

The boat is now noticeably fresher when first opened. 
It is surprising how little air movement is required to really improve the health of the interior.  As an example, our first boat (an early 70's Venture 222) suffered from condensation and mildew above its v-berth until I installed a small passive dome vent in that area.   Was amazed that this yard-sale item solved the problem.
Overall these solutions have worked well.   That said, I am not convinced that the day and night vent is worthwhile or could stand up an any sort of demanding situation.  It is threaded into a thin plastic collar, will need batteries replaced, and will require jury-rigged solutions when the hobby-quality motor or switch fails.    Ok for an RV maybe, but a really sturdy, offshore-quality passive vent might be a better investment.  I'm kinda glad i located it where it is unlikely to be kicked, snagged or stepped on, and when it fails I may replace with something more in keeping with the quality of the rest of the boat.