sub build underway christmas 2011

I haven't built submarines, though the riggers who taught me many good things like Charlie Anderson and Joe Soames came from submarine yards Electric Boat and Mare Island respectively, I've "sunk" subs in ASW warfare with hand grenades for "depth charges" back in the 60s.
You drop the grenade, it goes pop under water and the sub releases a dye marker and if you take a photo of the grenade bubbles and dye marker together you've "sunk" a USN submarine.
Our CG cutter USCGC MATAGORDA kept "sinking" them better than the Navy destroyers did so they wouldn't play with us any more.
That was certainly easier than trying to do this.
As to heavy workboat (tugboat) building, that was my apprenticeship with Don Arques in the 70s.
Are you re-inventing the wheel on this also?
Ferro cement tugboats?

 

OK- going back over some of the mess of concrete sub debate.

I invite anyone to read this post and take what they will from it over the implied difficulties in home built submarines:

http://www.boatdesign.net/forums/boat-design/concrete-submarine-24361-25.html
Read my post #367

By altering the text of that abstract Wellmer removed that parameter which would make a home built concrete submarine a virtual impossibility.
So he is not even copying existing proven requirements.....

Proceed with great caution anyone following his lead.
I am betting the the Troll platforms he loves to quote as being proof of concept are also Pre-stressed.......

Edit- yes the Troll platforms are all prestressed construction.

So Welmer decided to skip that bit- no bother.. probably not too important anyway eh?


"It was found that both longitudinal and circumferential prestress must be used in the construction of the pressure hull."

 

poke hulls!?--good one --was it an intended pun??
hey yea --go ahead i like hearing debates too...in a lot of ways i am like Wil..
I know none of this is personal-i want my tugboat--probably my second or even first fav dream...ill sharel- that the reason i liked a sub was that it seemed practical on many levels...but on further review that guy in the first few posts got me to thinking--"hmmm yea he is coprrect-the views are not like ON the water...it helped ease my pain.. i Would say this about Wil- he has taught me a hell of a lot...and he has come under a lot of critisism..and maintained his path where many-incuding me would have faltered...so thumbs up to him..

do you have a boat?

 

isnt prestressed just for adding tensile strength? in a sub its more compressive strength that is needed --the prestressing might be for military data since it has to withstand shockwaves from depth charges etc..i would not endores a military sub in concrete...it would shatter...

 

With all due respect, you started the thread saying

If you want to prove you can do it, by all means, do it and show us your successful launch.
We have nothing to gain by saving you from wasting your money if it doesn't work.

 

Hmmmm
you must have just missed my post
I know you have a lot of other questions your trying to answer.

So what about it. Considering for the varying rates of thermal expansion given thermally isolated materials, how are you planing on dealing with the "increasing" gap between the metal hatch ring and the concrete hull material, on submersion. Remember that metal rings been baking in the sun for a week or two and its insulated from from the hull temp by the sealant. So its probably at its tightest at the surface and loosens when you dive. Not the other way around. Maybe once you hit a sufficient depth you will start making up for the contraction of the ring once it hits the cooler water but all in all unless you calculate that expansion and provide a sufficiently structural seal that can accommodate for that amount of movement then I'm a little fuzzy on how you think your going to end up with a submarine rather than a very expensive artificial reef. Then there's the issue of all the other through hulls, like propellers and planes. Deal is this issue is absolutely critical and yet it seems like you might be avoiding it. Although its certainly possible you just missed my post.

I suppose you could not use a metal hatch ring and just set the hatch right on the concrete but that just doesn't seem like a very safe plan either. One chip and your taking a bath.

Do you have any detail drawings of the hatch area you could present to us. Its these type of details that will make or break your feasibility study, or are we skipping that as well?

oh almost forgot
most sealants don't do particularly well under cyclical loading either, they tend to get forced out of the joint eventually.

 

no Baatan, only steel for my tug - I can weld- and when designing my sub - called so many places trying to find affordable 6 ft dia pipe with 1/2 inch wall thickness..this was because i wanted to have ease of build in steel-being able to weld everything together--i found an older propane tank 1/2 inch thick..i could have made a great sub with that but the dia wasnt large enough at only 5 ft. trouble was moving the steel hull was like again 4000.00 and to do it on a shoestring it didnt make sense. 6500 was the lowest i could find for 1/2 inch x 20 ft long...so it justified costs to go with ferr-cement using polymer modified types at twice the compressive strength of concrete--nope im a steel guy when it comes to tugs--so easy--you just weld things on and presto--they become part of the hull...i built a wood epoxy boat this summer and i'd never do it again --hate -i repeat hate working with epoxy and wood. cant do a boat right side up either the epoxy needs to be thickened and it still drips on you..its also mega costly..so steel----thats the most cost effective and the easiet least time consuming way to go for my project--stell is still the best bang for the buk for a boat --many wood guys would sell me up the river for that...but i 'em what i 'em...steel lover always--dont let the sub build fool you-- i would have used steel if i could have afforded it

also i tried to look into a typeXXI design which had better surface running characteristics but the problem became--the Length to beam ratio wastoo small--the sub would have been 75 ft long and 6 ft wide...id rather have a steel sub..but the costs were three times that of concrete just for the hull I should post the quote i got--52 ft x 7 ft dia. 27 000 plus taxes!! ferr-cement- 4000.00-6000.00 completed hull so cost was a motivating factor...the tug-i can do it for 10 000..!! and i can prove that too! on a budget sheet...
of course its flat bottomed so that helps...

 

Does anyone have a link to one which has been successfully operating for any period of time?

 

good question...bpl

 

***I could do one up on rhino--and id happily do that but but im absorbed in my tug build right now--it takes time to engineer something like that..but its doable i think..i believe the best way is to weld a pipe to the armiture first cement over it-then weld the hinge to the pipe...

 

the thing is concrete and steel expand and contract at almost identical rates...

 

I mention the hatch because its the largest of the through hulls but there's going to be more than just the hatch, which maybe you could do in concrete, although I'd never trust my life to a small wafer of concrete floating in a gasket. What about the prop shaft through hull. Thats surely going to have to be metal in order to get a good seal. same problem there. As well as at the dive planes and the periscope. If you want windows your really in trouble. Those will need real frames as well.

Anything that pierces the surface when at the dock is going to be subject to thermal expansion issues because that pesky sun is going to be beating down on it all day, day after day.

I'm thinking you might want to spend a few evenings crunching numbers to determine what the gap actually is and to figure out if maybe this isn't why no one else is building concrete submarines

 

not when one is baking in the sun and the other is mostly in a nice cool water bath

concrete has a K rating so even if some of it is above the surface in the sun it will still maintain a relatively stable temp throughout the material. Your metal hatch on the other hand will be isolated thermally from the concrete by the sealant ( you are going to use some form of water proof sealant on all the through hulls, concrete doesn't exactly form a great bond ) and also be baking in the sun. Its going to expand, a lot. Your concrete isn't because the water will keep it nice and cool.

your not going to end up with a stable joint between the two and so your going to have to allow for that expansion. That and your going to have to design a water tight expansion joint that can also handle the pressure at depth

I'm really curious as to how you plan on dealing with that

 

If the motors and batteries were outside as is standard in research subs today and all viewing is video only, you could conceivably have only one hatch and several small packing glands for control and video wires.
Only need for conning tower is to keep the hatch above the water when at the surface.
This can be a light, free flooding structure and the actual hatch at the hull.
This would also shade the hatch from the sun.

 

Having done some diving in the usual 6 foot visibility, I wonder why anyone would want a sub, especially a slow one.
I mean, all the murky water looks the same.