Myles,
I would have the additional problem of having to compensate for the density of my materials. That I can do with lead, but I cannot escape the continuing internal volume problems..I am having to go smaller and smaller as a result.
Joe
From: Myles Hall <myles.h@sasktel.net>
Reply-To: personal_submersibles@psubs.org
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] Free Flooding Spaces
Date: Wed, 16 Nov 2005 13:11:11 -0600
Joe,The bouyancy of all your 1 atm structures is what provides the ability of the sub to float with everything else attached. In other words, for eg, if your displacement of all your 1 atm compartments was 6000 lbs, then the TOTAL weight (including fairing, motors, etc, etc, etc, as well as the actual pressure hull itself) must weigh 6000 lbs. If all your fairing weighs, say, 1000lbs, then that has to be subtracted from the 6000lb total, leaving you 5000 lbs for everything else and so on. If at the end of adding up the weight of everything you are too heavy, then your sub will sink and you will have to lighten it up OR add to it's displacement. If after adding everything up, you are too light, your sub will float = boat. The way I am approaching it is I am aiming to have the weight come in under the displacement. I will make up the difference in weight by adding weight to the keel until it = the displacement.Myles.----- Original Message -----From: Joseph PerkelSent: Wednesday, November 16, 2005 11:24 AMSubject: [PSUBS-MAILIST] Free Flooding Spaces************************************************************************ ************************************************************************ ************************************************************************ The personal submersibles mailing list complies with the US Federal CAN-SPAM Act of 2003. Your email address appears in our database because either you, or someone you know, requested you receive messages from our organization. If you want to be removed from this mailing list simply click on the link below or send a blank email message to: removeme-personal_submersibles@psubs.org Removal of your email address from this mailing list occurs by an automated process and should be complete within five minutes of our server receiving your request. PSUBS.ORG PO Box 311 Weare, NH 03281 603-529-1100 ************************************************************************ ************************************************************************ ************************************************************************
Paul & Dan (ref: your reponses below)I need to cut total interior floodable space by at least half. What everyone's been telling me has sunk in, the numbers aren't lying. Myles was correct, it's either a sub or a glass bottom boat.
If one where to consider the free flooding fairing idea more closely, how do you provide sufficient surface buoyancy for the structure without running into the same problems all over again?
These WWII boats do not "scale' down well and a short and stubby "caricature" shape would actually be easier to control. Damn problems keep rearing their ugly little heads!
Joe
From: Paul Kreemer <paulkreemer@gmail.com>
Reply-To: personal_submersibles@psubs.org
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] "Frankenboot"
Date: Mon, 14 Nov 2005 11:46:06 -0800
Joe, just writing to put in a plug for Dan's suggestion: that you first consider the displacement of your minimally sized dry compartment and then treat the rest of the vessel as a fairing. The fairing would add some displacement, especially being built of plywood but you'd have to get the whole thing into your target displacement. The first step would be to choose your desired dry weight and/or crew compartment volume. (10,000lb? which is almost 160cf.)
You could add in your maybe 30% reserve buoyancy (48cf) for good surface operation but those are just variable ballast tanks, mostly for surface use and emergency surfacing, right? They wouldn't add to the displacement of the boat and the whole thing really would weigh 10,000lb on a trailer.
This seems like a better way to describe a WWII-style homebuilt that will be good on the surface - a modest pressure compartment with a big free-flooding fairing. You could do a big deck and superstructure like on that nice S-44 replica, but you would need some propulsion power to move such a rig submerged!
Please correct me if I'm wrong on this - certainly there are different ways to approach the design process.
Paul
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Dan H. wrote:
Maybe your only planning to build a small pressure hull with a big fairing for your subs appearance. If so, then your displacement is only your pressure hull and the fairing can be free flooding and not part of your displacement equation at all.