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OD16 Glassbottom Project begins!

Posted: Tue Jan 10, 2006 9:46 pm
by Fishnchamp1
First off,... I've never built a boat, and now I'm building one with a hole in it on purpose :doh: Ok, now that thats out of the way... Has anyone ever done anything like this before? I searched the market high and low for a small boat with a glass bottom and just couldn't find one other than a lil dingy thing that couldn't hold two of me and an engine. With nothing much better to do but drink rum and tell stories, I've decided to go ahead and make this idea a reality. If anyone has any posts or weblinks to similar projects, I would greatly appreciate the knowledge. Again, sorry Jacques for the bastardization of your wonderful boat! :oops:

Check my gallery for some drawings and pics to get the creative juices flowing!

http://gallery.bateau2.com/thumbnails.php?album=426

Posted: Wed Jan 11, 2006 2:56 am
by ks8
I toyed with this idea a little when the suggestion came from a relative.

My thoughts were,

first, it has to be a boat with a large hull section that is basically flat already, that would easily be accessible for viewing underwater, and yet not be a heavy traffic area in the boat. And flat so that it would not freak out the water flow on the hull surface.

two, there should be a way to cover the Lexan when not viewing, to protect it.

Three, the hole in the plywood can't compromise necessary strength for intended hull performance. Stringers need placement to make up for the absence of skin strength that would have been provided by plywood in that section, just like headers in a house frame replace some strength in doorway and window cutouts where one stud or more is missing. Don't rely on the lexan to replace that strength!

Four, the installation must not be compromised by hydrodynamic forces while underway, such as being pushed up into the boat, or sucked out. If there's a rocker, watch out for bernoulli sucking it right out of the boat. The installation has to distribute loads well on the edges of the lexan so it won't fail at a screw hole or such.

Five, you must consider the different expansion and contraction properties of the lexan compared to plywood stabilized by fiberglass. It will expand more and shrink more with temperature changes. So some give has to exist horizontally in the installation, like floating panels in a wood door, and a flexible sealant used that can accomodate expansion and yet grip during contraction, and yet also be easily removeable for any necessary maintenance of the cutout frame or lexan, but also be utterly watertight. bolting to a more permanent gasket, and then applying flexible sealant in the edges might do it.

Six, fully research these points and lexan properties before proceeding since you must engineer the mounting mechanism and the sealant strategy to accomodate these issues.

Use lots of floatation foam to make recovery easier during R&D tests! 8O
And console yourself with the option of patching it with plywood and glass and cleat/butt blocks, as if it was a repair, should the experiment require more attention than you planned on giving it.

Seven, find out how others have suceeded or failed, and all the other stuff that in my ignorance and desire to go to bed now, that I have left out...

I like the idea, but I have a sailboat to finish first ... and 30 other projects ... :)

ks

Posted: Wed Jan 11, 2006 10:33 am
by Fishnchamp1
expansion, lol, great minds think a like! thanks for your input, i hadn't thought about the window actually being sucked downward away from the boat, but that is certainly a possibility. i will compensate during construction for this motion. THANKS! :D as far as sealants i was thinking of using underwaterline 5200, that stuff i think should provide all the sealent i think i could ever use and will have the properties you mentioned (with the excetion of easy removal :? ) LOL, as far as retrieval during R&D funny guy, may I'll just take you with me as a guinea pig!!! just kiddin, thanks again for the input!!!

Bill

Posted: Wed Jan 11, 2006 4:38 pm
by ks8
I didn't mean to sound too coarse about the retrieval... :?

Lots of floatation foam really isn't a bad idea, since you are attempting amateur engineering, which is not to speak lowly of it. Amateur athletes could whop me in just about any sport. *Amateur* may be very competent. But it is a boat, that may be out away from land.

Foam may be just the thing if the *surprise* should occur unexpectedly.

And of course... you will post more pictures, right?

ks

Posted: Wed Jan 11, 2006 5:27 pm
by Fishnchamp1
no worries ks, I'm just grateful that there are minds out there that have the willingness to help open mine up a bit! I will definately keep postin pics! 8)

Posted: Wed Jan 11, 2006 7:24 pm
by wingnut
Is that a late 60's Bug in that garage of yours? 8O Very 8)

Posted: Wed Jan 11, 2006 8:29 pm
by Fishnchamp1
1953 zwitter! Thanks! I have a Judson supercharger ive been meanin to put on it, just havn't made the time yet. Maybe I'll get 46 whole hp out of it when its done! 8)

Posted: Thu Jan 12, 2006 10:41 am
by flattie
fishinchamp1.
jacques suggestion to build a box that comes up above the level of the water line is dead on. Even if the glass/acrylic/lexan were to fail the boat would not sink. Many downeast or lobster boats have an access tube located in the rear deck above the shaft for when they get inevitably get gear tangled in their shaft/prop/rudder. Usually its a 6" diameter tube fiberglassed into the hull bottom that rises 2 or 3" above the resting water line of the boat that is capped off with a rubber boot secured with ss hoseclamps. If you get line tangled around your shaft you open up the lazarette hatch, remove the cap from the tube and reach down into the tube to free the gear from your shaft.
flattie

Posted: Thu Jan 12, 2006 11:30 am
by kiwi
Fishnchamp1 wrote:1953 zwitter! Thanks! I have a Judson supercharger ive been meanin to put on it, just havn't made the time yet. Maybe I'll get 46 whole hp out of it when its done! 8)
Like I said over on the Gallery I had a '55. It had well over 300,000 miles on the clock (MOT records to prove it...). Contrary to popular belief that 1100 does not burn much petrol - very cheap car to run. Cable brakes take a bit of getting used to but the old girl would get up to just under the 110 Km/hour. I drove it for a whole week without the clutch just using the key to stop and start at the lights. I never used the clutch to change gear after I got the new cable in. 8)

WTF does this have to do with boats :oops: Well VW does make marine diesels now...

Tony

Posted: Thu Jan 12, 2006 11:39 am
by ArizonaBuilder
How about one of these on the end of a pole that can be put overboard.
I great way to see the bottom for fish, your anchor and inspecting the hull of your boat from above. You can also use it to see outside your sailboat cabin, while holed up inside during bad weather or at night while sleeping.

CCD cameras are extremely cheap these days and your options are endless and all you would need is a nice waterproof case plus some power and a cheap monitor.


Image

Posted: Wed Jan 18, 2006 5:52 pm
by whitehawk
In the late sixties I had a wooden skiff I bought in Miami. Basically a flat bottomed skiff made from 1/4" plywood. I got the idea of a glass bottom from my woodshop teacher, brought the boat to school and we all made it our project for extra credit. Cutting the opening perfectly square was a challenge. We did frame the box with members running from frame to frame, leaving enough space for seating the glass and removable back-stays. Those were the days of basic caulking and non-tempered glass clad poultry wire. The rear seat was divided into three boxes with the glass to the far port section. Needless to say after a few beachings you couldn't see through the glass, and it was forgotton about for years. (got an "A" on the project though) Then in the 80's they came out with A.R.Grade Lexan.(abrasion resistant) We drug out the old skiff and put in a piece of that stuff and it worked great. Unfortunatly the transom pulled loose when we were launching in heavy surf and we had to leave the boat on the island (covered with branches) for the week until we could get a tow-boat out to tow it home. Of course it was gone when we got there. We asked the guys at the quarrantine station and they hinted that the caretaker of the Gar Wood estate probably dragged it home (down the beach) and we were out of luck. This is now called Fischer Island in Miami's government cut, where the Chalks seaplane recently went down. I would like to try it again though, with more modern materials.

Posted: Wed Jan 18, 2006 5:59 pm
by whitehawk
I forgot to mention, after cutting to hole and BEFORE installing the glass we took the skiff out for a try without the glass, figuring we could save some money.(kids) The moment we got underway the compartment flooded, funneling water into the rest of the boat, almost sinking it. I had to kill the power and jump out to swim it to shore without it's sinking.

Posted: Fri Jan 20, 2006 3:46 am
by kiwi
whitehawk wrote:I forgot to mention, after cutting to hole and BEFORE installing the glass we took the skiff out for a try without the glass, figuring we could save some money.(kids) The moment we got underway the compartment flooded, funneling water into the rest of the boat, almost sinking it. I had to kill the power and jump out to swim it to shore without it's sinking.
You jumped in the hole to walk it out? :D 8)

Tony

Posted: Fri Jan 20, 2006 7:05 pm
by whitehawk
I see where that might have been unclear. The rear seat was full width, side to side. The seat was divided into three equally sized compartments, each with it's own purpose. The viewing port was built into the PORT side compartment. We had omitted the glass, since it was still mounted in a door. We decided to take the boat for a spin, thinking no harm would be done since the top of the compartment was higher than the water line. HOWEVER, the motion of the boat under power funneled water into the rear of the boat via the viewing port. (insert sound effect) I jumped out of the boat (not the view port) and swam it (the boat) to shore. :roll: