Looking for some tips for a glass bottom boat design

All that doesn't make any sense. A simple study of floodable lengths would show the unviability of such a boat.
In ship design it is advisable to know something about naval architecture.

 

My pal Marvin here has been operating his 'traditional' (for Barbados) plywood glass bottom boat here for the last 20 years, and he earns a good living from it.
Here is a link to his Facebook page, which has many photos of the boat for general reference.
Marvin's Marvelous 1 | Holetown https://www.facebook.com/MarvinsMarvelous1

She is about 28' long, with an outboard motor of about 50 hp I think.
There are various glass bottom boats here, all basically similar in design to Marvin's, however Marvin's is the only one (so far....) that has a simple bow ramp for beach landings (it can also be used by swimmers) instead of a 'traditional' ladder on the bow.

Here are a couple of photos of Marvin's boat for reference -

This question is in regard to having an adjustable height glass box between the hulls of a catamaran - the box could be raised out of the water when underway or not in use (hence reducing the amount of fouling on it).
And then lowered into the water when the guests on board want to do some underwater viewing - it is only possible to do this at slow speed, as if the speed is increased, you will quickly get lots of bubbles passing by under the box, and the guests will be able to see very little.
This is just an idea I had - I have not seen it done before, but I think it should work well, if it was built.

 

Pick up 'Elements of Boat Strength' and 'Guogeon Brothers on Boat Building'. 'Elements' will give you minimum scantlings for common building methods and then you can do/find materials strengths on your specialty materials and extrapolate from there. I think for catamarans you'd use their scantlings for the hulls and then there's a different set of formulas for the platform. For a glass bottom tourist boat like that you'd probably want to work with an actual naval architect during the design and build who's probably doing the same calculations you should do but if coming from you insurance probably won't accept it, especially for commercial use (passenger liability)... although that depends on where you're trying to insure it.

If you are new to naval architecture it will be hard to winnow to the good advice from random stupid. Textbooks are useful.

 

@socalspearit the extrapolation that you indicate is a nonsense and, excuse me for being so abrupt but, that advice can lead to very big disasters. Not everything is feasible in boat design, you have to be much more rigorous. Excuse me, again, if I am very blunt on this topic.

 

I've been making flutes out of a clear epoxy called Craft Resin and they're strong enough to use as a martial arts baton. You could potentially make sections of the hull out of the stuff (a robust canoe that looks as if it's made entirely out of glass would be fully viable) and shape it however you like (curves and folds). It's highly scratch resistant, though you don't normally leave the stuff in sea water, so I don't know how long it would take for marine life to start growing on it, but if it gets too scratched, you'd simply sand down the outer surface and put a new thin layer over it.

 

Oh right, yeah, what I thinking. We've all done a proper lay-up on a wooden panel with 6oz S-glass and discovered it to be less abrasion resistant and overall flimsier than the same thing done with plain old e-glass.

 

Hello again everybody. Happy holidays, sorry i haven't been much active due to finals and holidays season (I am going on vacation too soon so that will also make me unactive for a while hehe) just want to say thank you to everybody that has posted I am reading every bit of it. Although some of the information still is a bit confusing for me to read and understand, but I'll try my best to look into if much further after I'm back home. Thank you so much for the advices I didn't expect there too be this much replies and i really appreciate it.

Just for some context I am very new to the world of marine engineering and this will be my first time ever in a paper competition so really any advices on anything even from the basics will help a ton. Also i would love to ask on some advises on the innovation that I'm working on the ship itself which are AI fish identification, Natural fiber composites, underwater lamps, hull fin and dynamic pricing. Once again happy holidays everybody wish everybody and their loved ones the best for the upcoming year 2025

 

I disagree. Having built a number of wood and foam strip canoes reinforced with various combinations of e-glass, s-glass, basalt innegra, kevlar and one craft with Zylon I will absolutely claim that S-glass is superior to E-glass in respect to all characteristics except cost.

 

Actually, I think everything socal has said has been misinterpreted.

First, he advised some reading so the OP realizes how difficult things are in reality. And his main point was to hire a NA. Of course, TANSL misread him or focuses on the wrong point and replies as such.

Then socal offers up sarcasm directed at TANSL.

I could be wrong. Sarcasm rarely reads on the interwebs.

signed, Peanut Gallery

 

You're probably correct, I had a knee jerk reaction, S-glass is one of my favorite boat related fabrics.

 

@fallguy, if I have misinterpreted something and, as a result, written something incorrect or that has upset anyone, I apologize a thousand times.
I just wanted to pass on two opinions:
- there is nothing in Dave Gerr's book that can be extrapolated to the design of glass-bottomed GRP boats.
- some people know something about 3 subjects and think that this entitles them to comment on 30 other different subjects. Having seen many photos of these types of boats on the web does not mean that they know how to design them. A glass bottom involves much more, and much more complicated, things than calculating the thickness of the glass or the structure that surrounds it. And bad advice can lead to very complicated situations.
And a third opinion: designing a structure is much more than calculating its scantlings. That is only the second phase.

 

Yes, I was being sarcastic.

We are all brothers on the water...

...BUT when doing the holidays with family and toddlers 1000 miles inland, I have no free patience.

Dave Gerr's book doesn't cover glasss bottom boats but honestly I don't understand why one couldn't take his hull calculations that create a certain hull stiffness, remove the section that would be glassed, possibly further stiffen the hull, make a frame of adequate stiffness for the glass, test it (jump up and down on it, subject it to various shears, etc, rebuild if necessary) and once satisfied put sufficient clear pane in it with an adhesive/sealer that will stick against the hydrostatic pressures and accomodate differences in thermal expansion, check specs carefully on the glass/polycarbonate, etc, of course and not try to go with minimum tolerance. I have thought about this for the family boat I intend to build. Such a thing would be perfectly USCG legal but not Lloyd's Rules and probably not ABYC.

There is a glass bottom boat in my harbor that has been operating and sitting in the water for likely 10+ years at this point. It's been through multiple owners. It's insured as a commercial charter. It doesn't do more than 7mph but it has delighted innumerable children. I'm going out on a limb but I have a feeling it was built kinda like I described above and there was no computer sims and certified naval engineering behind it.

 

Glass bottom boats have a bulkhead around it, so even in the case of complete failure, the boat won't sink.

 

You seem to know a lot about the subject. How do you manage to verify that the ship is not sinking? What types of damages do you study, what extent would those damages be? Can they be asymmetrical? How do you define/limit compartments? Do you use FEA, what software?

 

When the water gets above my knees, us sailors start running around in circles and screaming: We are sinking. Sailors and rats first!