Can Opening Ports be Istalled in these Windows?

[TacomaSailor]

We are again looking at the Erik Lerouge/Brazapi 51 here in San Diego.

The boat will be our only home and it will spend all of it's time in the tropics.

One of our primary concerns is the lack of ventilation in the main cabin. There is ONE 6" round port opening in the front on either side of the mast. The aft window in the main cabin will slide to create a 2' x 5' opening. And a "normal residential" size door opens inward.

We looked at the boat when it was about 78 degrees with a light breeze. The cabin, with everything open, was stuffing and had little airflow.

Is it possible to put in opening hatches, such as a small Lewmar Ocean Series hatch, into the rigid front windows. And, into the vertical rigid side windows?

How would I determine if those hatches would compromise the strength or integrity of the windows.

I have seen such an arrangement on big Lagoons and other production catamarans.

The captain of the boat when it was in south Florida said they just ran the AC all the time. That is not an option for us.

I have attached three pictures
- one from the bow looking aft
- one from the inside of the main cabin looking forward. That shows the port side window and the forward windows that are the port of the mast.
- one looking aft to the back of the main cabin

[JPA Cate]

Of what material and thickness are the forward facing port lights in the saloon?

And, is it compound curves, side to side and up and down?

From the pic, I wondered whether the timber-appearing uprights would be strong enough to support a hatch in a seaway. If so, then a real opening hatch might fit right there, and how cool! But concept will not work with compound curves.

Life being generally more difficult than that, do you know somewhere you could locate the specs for the Lagoon "windows" that do support opening portlights? I'm thinking you could upgrade the glazing (if necessary), then put opening ports in. Might worry about a big wave, though.

Another option would be to install dorades on the top of the deck house, and have 85% shade cloth covers made for the "glass". If you went with the dorades, you could use computer fans to make them suck the air in, and it will flow out that huge "back door".

In some ways more important, how would you manage the ventilation to the berths? (We use Caframo fans to move air around, now, as they are so very much easier to keep clean than Hellas.)

Or, could you cut an opening for a good hatch into the deck house? for both saloon and berths? Lets in lots of air, and you can make a hatch dodger for it that will allow you to keep it open in the rain. I made such an object for our forehatch.

Good luck with the project, but don't buy the boat if you can't ventilate it: the closer to the equator you get, the more you sweat, and you can only be comfortable if you can cool it. Just my 2 cents, I am not too comfortable with great heat and humidity, YMMV.

Ann

[UNCIVILIZED]

In terms of whether or not they'd compromise the strength enough so as to be a bad idea, your best bet would be to go to the source, & have conversations with the builder & designers. That'd be the definitive answer (assuming that is, that they're competent of course).
And be sure to get their answers & specifications on paper!

The questions which play into if it's okay to add cutouts to the windows, to add some hatches, is where are the primary load paths in the cabin structure, & what is built in where (underneath of the cosmetic coverings) to handle these loads.
The loads being from; the spar, the headsail sheets, the hulls wanting to twist independently from one another.

More than likely there is enough strength, but... if you goof, the repair bill wont be small. Especially as the built in windows could be/likely are, to some degree like the windows in a skyscraper, which carry a good percentage of the structural loads of the building.
- This is VERY likely the case, & another reason so speak with the boat's engineers.

When you inquire about cutting holes to mount opening hatches, also inquire about doing the same to mount Dorade Boxes/Systems. These needn't look like the old fashioned boxes per say, but can be lengthy, stylish, etc. Pretty much any shape that one can conceive of, & have several "cowls" (or scoops) again of varying shapes each. In addition to the box structures having several (sealable) openings belowdecks. So that fresh air can be directed to various locales based upon ones needs & desires.

The Dashews have gone so far with these on some of their vessels as to add ball style ventillators which can be used to direct the airflow, kind of like the ones in the dashboard in a car. With all of the air coming from huge, stylish, multifunction, deck boxes which look naught like typical Dorade boxes.

And the perk of Dorade's & similar, are, that when well designed, short of practically a hurricane, such units can be left open to let the breeze in down below. Even in a rain that would have you needing to close all of your hatches & ports.
You can also have a system of "powered" Dorade boxes constructed. Whereas, the air flow through the ventilation channels & ducts is simply provided for by a few low draw fans. Ones with small dedicated, low powered, solar panels, or a system which runs off of the house battery bank system.

I can tell you that I was flat out amazed by how much difference just one, 4" solar powered mushroom ventilator made in the cabin temp & humiditiy in my Ranger 33. So with wise design, it needn't take a lot (of fans or power).

One other question & or info bit relating to the cutting openings into your windows, for hatches & such. It might be necessary, and or just plain old wise, to have some structural stiffeners made & bonded to the interior of the vessel. & the wrap around structural windows, so that the size of the area of each unsupported panel/piece of windshield, aren't so large.

The reinforcements could be metal (bare, painted, or powder coated), metal enclosed inside of some gorgeous wood, or even, sexy, clear coated carbon fiber.
And these reinforcements could simply be; bonded to the windows, bonded & bolted to them, & ditto on the same to the surrounding fixed structure(s). The perk of the bonding only option is that it's still a very clean look.

Another option is to have strengthening rings manufactured to be only slightly larger than the hatch cutouts, & then bonded to your current windows, prior to making any openings for hatches.
Keeping in mind that round openings create smaller stress risers when cut into materials than to square or rectangular ones. As with them, the loads spike at the corners.

Lotta' info, I know. Chalk it up to insomnia mixed with an engineering background... of a long time sailor.
Good luck with the project. And ESPECIALLY enjoy the new toy/home... plus your upcoming travels.


PS: Gorgeous boat BTW. If you ever need a sailing master, or a deck hand... I have tools & do travel ;-) That & it seems that once again, Ann T Cate was typing some of my thoughts at the same time I was.

[JPA Cate]

Thanks for the kind words, UNCIVILIZED, I always try to write simply. Sometimes I get all tangled up. I think your above advice is sound.

Ann

[UNCIVILIZED]

Ann T. Cate,
Thank you for the kind words as well. I know I'm still new around here, but I've yet to run across one of your posts which isn't both well thought out, informative, & informative in such a way that it's easy to understand. Not to mention a good read.

And yes, I agree. Some topics can be a bit tough to write about without getting overly long or technical in ones reply. This is definitely one of them for certain.

[HappyMdRSailor]

I've got a similar "Sauna Sun Room" arrangement, and can tell you that you've never experienced hot and stuffy until you've opened the companionway hatch on a smokin' hot humid day only the South can muster! (that's my brain melting, not confusion)

Two things:
1. We have (2) 14" coachroof hatches... Opening these drops the temp 20+ degrees in 3-5 minutes... I don't see anything crazy load wise there on your boat, but the warnings given would make me do some research to be sure... One thing I would change is turn one of the hatches 180 to open aft... Also, all of our hatches have a screen/shade slider... Very important...

2. Window screens... We have black rubberized mesh screens that snap in place over the windows on the outside... It's honestly still shocking how much they lower the heat transfer to the saloon... We leave 'em in place constantly... There is almost ZERO difference in loss of view from inside, 10%? Outside looking in, 90%... Almost impossible to see inside without the right angle and distance...

[Delancey]

Originally Posted by UNCIVILIZED

Like the windows in a skyscraper, which carry a good percentage of the structural loads of the building.

Interesting. Never heard of such a thing. The only loads I have ever heard of a curtainwall glazing system carry was it's own deadload plus windload. You make it sound like the glass is holding the building up or something. If that's the case why the need for all those pesky steel columns everywhere? Just curious.

[Dockhead]

Originally Posted by Delancey

Interesting. Never heard of such a thing. The only loads I have ever heard of a curtainwall glazing system carry was it's own deadload plus windload. You make it sound like the glass is holding the building up or something. If that's the case why the need for all those pesky steel columns everywhere? Just curious.

Delancey is correct. Nearly all tall buildings today use curtain walls, where neither the windows nor any other part of the external skin of the building carry any structural loads at all, other than wind and their own weight.

See: Curtain wall (architecture) - Wikipedia, the free encyclopedia

[Sand crab]

Worked on a few tall buildings. They were already standing and then the glass went in.

[HappyMdRSailor]

Originally Posted by Sand crab

Worked on a few tall buildings. They were already standing and then the glass went in.

Tall buildings in Bozeman???

Are all the hitching posts and saloons gone ???

[Delancey]

One of my personal favs, the Comet. Square windows seemed like a good idea at the time. After 13 fatal crashes airliner windows have rounded corners.

De Havilland Comet - Wikipedia, the free encyclopedia

[UNCIVILIZED]

To explain a bit of how some boats are built, & give an explanation to my earlier post, there's another long'un below. My apologies for taking up so much screen space, & or if I oversimplified things a touch. But in my travels, I've found that more often than not, it takes a bit of explaining before folks understand the how & why behind what holds boats, etc. together.

On a big catamaran, the entire cabin structure is essentially part of a monocoque "box beam" which both carries/distributes the stresses of connecting the hulls. In addition to being a major supporting member of the base structure which handles the loads from the rig.

The cabin is at the center of where the shrouds come together, so you have both big vertical & horizontal loads from that alone. And with some types of rigs, the vertical loads can be greater (sometimes by multiples of) the boat's weight. Not necessarily quite so much with a cruising cat as say with a racing Maxi mono, but... let's just say that those wires which hold up the mast are big for a reason. And that the loads which they both generate, & carry, have to be resolved by equal forces & structures elsewhere.

As to the cabin's roof, you have the loads from the jib sheets being resolved by the cabin top & how it connects into the hulls & the monocoque structure mentioned before. And on a boat that size, jib sheet loads aren't small.

When the designers/engineers are designing things to handle these loads, in a boat like this, often enough it's by adding extra glass cloth or carbon into directional load carrying pathways (as well as omnidirectionally). The same as you can see the heavier load paths in a sail, by following the densities of the patterns of the tapes/extra fibers in a tape drive/laminated sail.

So if you happen to cut, or take a chunk out of one of these areas of extra reinforcement, bad & very expensive things can happen (as semi-alluded to in my earlier post). Which is why I strongly recommended speaking with the boat's builders, prior to reaching for the power tools.

It's kind of like if you've ever pulled out the headliner in a car, & can see where the extra reinforcing beams are welded to the inside of the car's metal skin. And in some cars these beams cross over the areas where the driver & passenger sit. Which is why in cars of such construction don't, and cannot have sun roofs. It just doesn't work structurally. And were you to go ahead & put in a sun roof despite this, the whole car would be as flexible as a slinky when driving down the road. And at a certain point, the other structural metal would become fatigued enough that the vehicle would bend sharply under the floor, until it's underside was grinding it's way down the pavement at 60mph.

AKA, something to avoid in a $1,000,000 sailboat, upon one's lives may depend.

Originally Posted by HappyMdRSailor

I've got a similar "Sauna Sun Room" arrangement, and can tell you that you've never experienced hot and stuffy until you've opened the companionway hatch on a smokin' hot humid day only the South can muster! (that's my brain melting, not confusion)

Two things:
1. We have (2) 14" coachroof hatches... Opening these drops the temp 20+ degrees in 3-5 minutes... I don't see anything crazy load wise there on your boat, but the warnings given would make me do some research to be sure... One thing I would change is turn one of the hatches 180 to open aft... Also, all of our hatches have a screen/shade slider... Very important...

2. Window screens... We have black rubberized mesh screens that snap in place over the windows on the outside... It's honestly still shocking how much they lower the heat transfer to the saloon... We leave 'em in place constantly... There is almost ZERO difference in loss of view from inside, 10%? Outside looking in, 90%... Almost impossible to see inside without the right angle and distance...

[Delancey]

I'm no DaVinci. Looks like a hatch forward in this picture of a sistership. I would start with these and worry about the sides later. No point in re-inventing the wheel.

That said, I would be surprised to see any engineer expect fixed portlights on a boat to carry any structural loads, which means if you can find a way to install an opening port into the fixed ports without compromising their ability to keep the sea out, then you are probably good.

I have seen a similar installation before, have to remember which boat and will post later.

Usually, fixed portlights rely on flexible adhesive, possibly backed up with screws through oversized holes, because the acrylic or polycarbonate to make the fixed portlights expands and contracts due to chafes in temperature at a greater rate than the "load bearing" structure they are attached to. If your port lights are installed with a flexible adhesive, they are probably not structural.

I would advise against square corners.

[Delancey]

Meh, can't recommember. Seen it before on a production boat, maybe an older Bene or Jenneau?

Worst case scenario you have to upsize the thickness of the deadlight.

To answer to OP's question, yes it is possible and has been done before. Not likely your fixed portlight was designed to carry your rig loads.

My main concern would be aesthetic. Gonna look like you cut a hatch into your perfectly good windows.

In the meantime here's someone selling a Beckson cut into a deadlight.

Cruising Concept's Beckson Port Upgrade - YouTube

[Delancey]

When I look at a typical hatch section, I have to wonder if a hatch isn't both stronger and stiffer than the typical FRP layup into which the are installed. This begs me to ask that you wouldn't actually be strengthening a typical fixed portlight installation by cutting a hole in it and installing a hatch?

At the very least you are reducing unsupported panel area. Wouldn't you also be adding the strength of the halfch frame itself? No?