Adding port light into hull side.

[BAD ORCA]

Has anyone ever cut a hole in the side of their hull to add a small port window? I have a forward facing navigation desk at the bottom of the companion way. I always loved boats like the Jeanneau Gin Fizz and the Dufour 35 that had a nice sized port light at desk level at the nav desk. I always fantasized about adding one some day to my boat.

Has anyone ever done this and added a port to some location on the side of their hull that did not have any originally? Assuming its an oval'ish shape with no sharp corners, any reason why this would be a bad idea? I'm thinking of something like ~18 x 8" port. My hull in that area of the nav desk is 3/8 to 1/2" thickness. I would think the biggest concern would be making sure the hull was flat enough to be able to get a good seal. Structurally if i were do attempt to do something like this, I would epoxy bond a 1/2" thickness G-10 flange around the cutout opening on the inside of the hull and through bolt the window frame through the epoxy flange to add some structure back into the hull.

Just throwing around the idea in my head right now. Its not something i'm going to attempt if its questionable structurally, but may consider a year or two down the road if there are no real reasons why it could not be done safely. Anyways would appreciate any thoughts on this...

 

[dlochner]

Your concerns about the shape of the hull are appropriate, a smaller port may be a better idea.

Ran Sailing posted a video recently showing how they mounted a port light on the hull. It might be helpful.

 

[BAD ORCA]

Your concerns about the shape of the hull are appropriate, a smaller port may be a better idea.

Ran Sailing posted a video recently showing how they mounted a port light on the hull. It might be helpful.

Oh nice. I will have to give that a watch.

 

[PaulK]

You will notice that the title of the video is "Making big holes in the hull..." and that the porthole they show is considerably smaller than what you propose and reinforced with a metal ring around the edges. Waves hitting the new portlight have to be taken into account. How thick will the lens have to be so as not to shatter or flex, which would likely break the seal around the edges. When the rail is buried how deep will the opening be and how much water pressure will be pushing against the seal? The topsides portlights in production boats have been carefully engineered and are part of the construction process. DIY calls for what would seem to be a lot more homework first.

 

[BAD ORCA]

You will notice that the title of the video is "Making big holes in the hull..." and that the porthole they show is considerably smaller than what you propose and reinforced with a metal ring around the edges. Waves hitting the new portlight have to be taken into account. How thick will the lens have to be so as not to shatter or flex, which would likely break the seal around the edges. When the rail is buried how deep will the opening be and how much water pressure will be pushing against the seal? The topsides portlights in production boats have been carefully engineered and are part of the construction process. DIY calls for what would seem to be a lot more homework first.

Good points, yes I agree. I have since decided that 18 x 8 is way to big. After more consideration and measuring the space where it would go, I think i would keep the maximum size no bigger than 6" height x 14" width. Probably closer to 12 x 5". I think Lewmar and Bomar had some non-opening windows in that size or close to it. The radius of the hull might limit the width i could install. I haven't checked that yet. I could even custom make a port if i had to. It would be a bit more involved, but not terribly difficult. If i custom made it, i could control the size and thickness of the flanges and the plexiglass a lot easier. This would make it tougher and stronger against wave strikes. This might be what i eventually do if i actually follow through with this project.

I think reinforcing the hull will be pretty easy. It will be a little destructive though. If i do this project, it will be done when i rebuild the navigation desk which is a project i'm absolutely going to do.

My thinking would be to epoxy a 1/2" thick piece of G-10 or FRP around the opening of the port/cutout on the inside of the hull, with a 3" flange all around the opening. Onto this i would mount the inside of the port flange which i would custom cut from 1/4" stainless. It would match the G-10 flange and have a 3" flange all around the opening, but it would also sandwich and seal a piece of 1/2" thickness plexiglass. Through bolts would pass from the outside of the hull/exterior flange through the hull and into this stainless backing plate on the interior.

Thats the general idea so far. The addition of the G-10 and stainless flanges i'm hoping should add back in the lost strength from the cutout. Its in an area of the hull that i can imagine see's any real stress or flexing. My nav desk is set back at the companion way with a couple of beefy partial bulkheads in front of it, and a full bulkhead directly behind it. Standing rigging is well forward of this part of the hull. Thats my assessment so far...

 

[Dave]

What is the hull thickness at proposed port location? It would be easy to create a hard spot where the G10 and hull meet. I'd consider a thinner piece of G10 and then fiberglass that to the hull with a taper to ease the transition.

 

[BAD ORCA]

What is the hull thickness at proposed port location? It would be easy to create a hard spot where the G10 and hull meet. I'd consider a thinner piece of G10 and then fiberglass that to the hull with a taper to ease the transition.

Interesting, i didnt think of that. Its a hair under 1/2" thick in that area.

 

[colemj]

I put a 15x8" opening hatch in our hull.

I think you are over-thinking the structural and strength issue wrt the hull. Just look at the boat molds with hull ports - they just have a plug in the mold where the ports will go, then do a normal layup over this leaving the core out of the plug area, and cut out that area when the hull is out of the mold. There isn't any real structural design focus on these areas. Attached is a pic of a Catalina 316 hull mold showing this.

Many of them don't even do the above. They just cut holes in the hull where they want ports and install them.

Your hulls are strong enough, and the main strength to the boat is provided by bulkheads, stringers, liners, and other components that are designed to support a skin. The skin needs to withstand oil-canning, but any structural support will not be compromised by relatively small holes like you propose.

In the same vein, you don't need to worry about "hard spots" installing a frame around it. The hatch frame itself is a "hard spot".

The above assumes a boat designed with proper scantlings and layup, and not something like a Macgregor. For sure there would be no problems on a Mariner 36.

Mark

 

[colemj]

That Catalina pic with the port plugs wasn't very good quality. Here are some other examples, including what the ports look like when the hull is removed from the mold. Note that one of the examples is a male mold, where any additional hull reinforcements around a port aren't practical, as the port positions are areas where an external frame plug is employed, and the layup just occurs around it.

 

[BAD ORCA]

I put a 15x8" opening hatch in our hull.

I think you are over-thinking the structural and strength issue wrt the hull. Just look at the boat molds with hull ports - they just have a plug in the mold where the ports will go, then do a normal layup over this leaving the core out of the plug area, and cut out that area when the hull is out of the mold. There isn't any real structural design focus on these areas. Attached is a pic of a Catalina 316 hull mold showing this.

Many of them don't even do the above. They just cut holes in the hull where they want ports and install them.

Your hulls are strong enough, and the main strength to the boat is provided by bulkheads, stringers, liners, and other components that are designed to support a skin. The skin needs to withstand oil-canning, but any structural support will not be compromised by relatively small holes like you propose.

In the same vein, you don't need to worry about "hard spots" installing a frame around it. The hatch frame itself is a "hard spot".

The above assumes a boat designed with proper scantlings and layup, and not something like a Macgregor. For sure there would be no problems on a Mariner 36.

Mark

Thanks Mark. Ha! you might be right. I definitely over think/ over build everything. Thats really good stuff though. Thanks for sharing. I had no idea thats all they did. I have seen boats with hull ports, but its impossible to see what they did on the hull because its all covered up on the interior.