Best way to mount a dome to the hull

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rvanscotter
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Best way to mount a dome to the hull

Post by rvanscotter »

Adsvice,

I bought a Ikelite 5810 housing to use as my hull and I ordered a 3.5" dome from cleardomes.com. My question is what is the best way to join the two and create a good seal. The Dome has a 3/8 in flange on it and I was thinking of screwing it to the hull with an aluminum ring to distribute the tension evenly. I think the hull is only 3/8 of an inch think so that doesnt leave a lot of room for screws. I could set a 6 or 8 helicoils in it, but I wonder how much that will compromise the structural integrity. What about a flat gasket? or should i just apply a thin film of silicon as I seat the whole thing?

Opinions please?
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bikerbones1968
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Re: Best way to mount a dome to the hull

Post by bikerbones1968 »

Assuming your hull structure is perfect square and flat use 3M polyurethane adhesive/sealant between your dome flange and hull. Screw it down with multiple small stainless screws. This is how a lot of dive camera housings are constructed and the quality ones use the 3M sealant.


http://www.ebay.com/itm/3M-Marine-Adhes ... 0504081848
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rvanscotter
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Re: Best way to mount a dome to the hull

Post by rvanscotter »

Perfect!

I got my hull today, and it was cracked! It will be replaced by B&H, but I'm waiting again now. The mounting surface is 5/8" thick and I was going to set 12 1/8" helacoils into it and then screw some stainless screws into them. I was also thinking of making a 1/8" thick aluminum rim to go over the mounting flange.

I will order some 3M Marine right now.
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bikerbones1968
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Re: Best way to mount a dome to the hull

Post by bikerbones1968 »

Does that enclosure have an O-Ring assembly that the cover/lid clamps down on?
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rvanscotter
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Re: Best way to mount a dome to the hull

Post by rvanscotter »

Yes it does, you can see it in the picture. The housing is good to 200' and the face plate is 5/8" think. I'm surprised that it cracked
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bikerbones1968
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Re: Best way to mount a dome to the hull

Post by bikerbones1968 »

This quick release cover design is similar to my Hull setup although I am using Rigid Schedule 80 PVC with a fibreglass lens cradle and the same style oring groove seal.

(See a few photos of it here viewtopic.php?f=13&t=732 )


I guess what I am trying to understand is are you planning to attach a camera dome to this assembly?

If so I am wondering why you would cut a hole in this enclosure to affix a dome? If you have room for all your internals including a camera it would be a shame to cut a hole in such a nice enclosure and potentially create a leak where none exists. Many underwater dive camera housings use a flat acrylic lens in front of the camera and work fabulously. Just an opinion....
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rvanscotter
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Re: Best way to mount a dome to the hull

Post by rvanscotter »

I saw your design an got to thinking that a housing would be a great hull. The 5810 is as big as I could find for a reasonable price. I should be able to get a everything to fit in it alright. You make a really good point, the face plate is perfect for a video camera. In a purist view the dome is not needed, I do like the idea of a pan tilt board camera in a dome and the aesthetics of a dome. Because I'm only building it to reach 100' I'm hoping I don't run into a leak problem. I spoke to a tech at Ikelite and he gave me some tips to drilling and sealing the housing. The face is 7/8" thick with 1/4" recessed into the hull. I was going to tap a dozen holes 3/8-1/2" deep into the faceplate and bolt the dome directly to the dome sealing it with 3M Marine. I figure I could also put a small o-ring on the bolts and silicone seal the outer flange as a precaution. To me it seems overkill but then again it's just a guess.
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bikerbones1968
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Re: Best way to mount a dome to the hull

Post by bikerbones1968 »

I do have a dome on the forward end of the ROV. I will use only a tilt camera setup and not pan. I found when testing camera functions pan was unnecessary. The field of view horizontally for my board camera is nearly 20 feet. Unless your lighting system physically moved while panning the camera you wound up looking into complete darkness.

My dome is permanently sealed with multiple 1/8" stainless machine screws, drilled and tapped directly into the PVC only 3/8" deep. A 16 gauge stainless steel trim ring is used to evenly distribute the tension and 3M 5200 sealant between the PVC and dome. My theory is that the deeper you travel and as more external pressure is applied you get a tighter seal. I have found by testing various designs over the last three months that you really need very little force to secure domes or aft ends so long as the faces are perfectly flat and smooth.

If you have the room, I would at least try your enclosure as is. If you were not happy with the results then consider adapting the dome to the enclosure. Also I think 3/8" mounting bolts are probably way larger than necessary. My hull and setup has now been tested to 150 feet for one hour intervals four consecutive times with not even a drop of water.
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