Gurps vehicles to design boats?

[hal]

For what it is worth, I finally DID purchase the Revell HMS VICTORY model and the measured beakers in ML values.

Once I get around to taking the five hull halves and gluing them together - I will be able to have an approximate internal volume. The real problem will be translating Milliliters into values that can be converted into cubic feet.

Finally opened the box and examined the hull elements for the ship model. As a VERY nice surprise for me was the fact the model hull comes in five parts. The first two parts are the lower Hull portion that is copper plated. I can glue those together and get the lower hull volume up to the copper plating. The next two parts of the hull are those parts that are above the waterline. The fifth part is the aft portion of the hull that is the stern "plate" as it were. Ie - it is flat and the portion above the waterline. I can effectively gain two measures for volume, below and above waterline values. KEEP in mind, that this is only an APPXOXIMATE value, as I doubt it will be accurate to within a square foot. My only regret is that this model is not of the same scale as my Black Seas ship models - which are rated at 1:700. My final HMS Victory model will be not quite twice the size of those models scale wise.


Scale: 1" inch on the model equals 450" in real life.

Thus, 1" cubic inch in real life for the model should equal 450 x 450 x 450 cubic inches or 91.125 million cubic inches or roughly 52,734.375 cubic feet.

Since 1 cubic inch is about 16.387064 milliliters, it should be a simple math calculation where I measure in Milliliters and divide by 16.387064 to derive how many units of 52,734.375 cubic feet the hull in general, should be close to.

At that point, I should simply be able to start with THAT figure for the size of the hull for the warship and proceed from there. All material for the ship's hull will be presumed to reside WITHIN that volume in general. Since we can use the formula where we know that a given density of Oak in cubic feet - we should be able to derive how much volume is lost due to the oak construction materials (per GURPS VEHICLES that is) and the remaining volume would be for holds, gun decks, wasted space, etc.

**Special note**

Having recently visited the USS CONSTELLATION, and banging my head at least 5 or 6 times, and having to stoop bent over in half, twice in order to maneuver within the ship's hull - wasted space won't be wasted by much! If you want to see what a "captain's private head" looks like aboard the USS CONSTELLATION, let me know and I'll forward you the pictures I took.

One of the questions I asked the guides on deck about, was how often did the ships have to replace their spars. The response was, in general, once per month depending on wear and tear (aka weather). Ships in port of course, didn't suffer that kind of wear and tear. One of these days, I should dig into my book for the dimensions of the Spars used by the HMS VICTORY and determine its weight based on the density of the wood and its calculated volume of wood. As a "guess" - it won't be spot on, but it will at least give me some idea of how much such a beastie would have weighed.

[fredtheobviouspseudonym]

Suggestion; books for reference.

Howard Chapelle: American maritime historian. Worked at the Smithsonian Institution for decades. Guru (technology) of the American Sailing Navy.
I recommend his books: The History of American Sailing Ships (1935); American Small Sailing Craft (1951); and especially The Search for Speed Under Sail: 1700-1855(1967) [included merchant vessels from colonial era to clippers. Contains tables on best information available data for gross tonnage (total interior volume of ship in 100 cu ft tons). Quite accessible. Also includes the hull plans of certain ships; should allow rough calculation of submerged volume.

D. K. Brown; British naval technical writer and onetime active ship designer for the Royal Corps of Naval Constructors, retiring as Deputy Chief Naval Architect. If you have interest in more modern vessels. Suggest; From Warrior to Dreadnought; The Grand Fleet; and From Nelson to Vanguard. Books have information on submerged volume for numerous (but not all) RN warships and good, understandable descriptions of hydrostatics and stability.

Norman Polmar: His Amphibious Warships; a Design History has lots of information on gross tonnage of 20th century ships closely related to merchant vessels. Contains profile plans that will allow an idea as to how much volume is submerged at standard draft.

Won't allow exact calculations but will allow pretty good ballpark estimates.

Also The Age of the Galley: Mediterranean Oared Vessels Since Pre-Classical Times (Conway's History of the Ship) lots of technical information on ancient galley designs & info even into the Renaissance.

[fredtheobviouspseudonym]

Originally Posted by hal

One of these days, I should dig into my book for the dimensions of the Spars used by the HMS VICTORY and determine its weight based on the density of the wood and its calculated volume of wood. As a "guess" - it won't be spot on, but it will at least give me some idea of how much such a beastie would have weighed.

IIRC the Anatomy of the Ship series for The 50 Gun Ship, HMS Bellona (74 guns), and HMS Victory has tables for spar sizes & weights, distances from waterline to lower sill of lower gunports at different levels of ship loading, anchors, boats, and major cables. From RN records.

[Polydamas]

Sounds like a fun project! I agree that measuring the volume of a model should be plenty accurate for a tabletop RPG. Real shipbuilders have more detailed and specialized models that use more complicated math or more computing power.

[hal]

Sorry for the delay...

First, I purchased a set of plastic beakers that measured in 1000 ml volumes, but the lowest first measurement line was 100 ml, and I needed something more refined. Consequently, I had to wait until the newly ordered smaller measures came in.

Second, I purchased some glassware beakers, the smallest of which was for 50 ml, and I was able to get a one time measure of just shy of 30 ml for the lower hull assembly. Call it 29 point something. I will likely measure this a few more times and take the average measure.

Now for the fun part. The model itself, as far as the hull goes, came in what amounts to five parts - six if you include the spar (or weather) deck piece. The lower section of the hull assembly, is simply that part of the hull with copper plating. The upper hull assembly is comprised of the spar deck plate, the starboard side, port side, and stern (essentially a plate). During assembly, you glue the upper assembly to the lower for a final completed "Hull section". It would have been nice if the upper assembly were water tight, but alas, it is not. I'll have to take some time to consider my next move. If I'm right, I will have to find some tape to cover over the section of the spar deck that is open to the next lower gun deck (loading cargo into the ship from the weather deck). Then I will have to use some putty to cover over the other areas that aren't water tight, accepting that by doing so, I will throw off my measurements by between 2 to 5%

Sadly, I don't have any modeling putty on hand, will have to try and find either a specialty model shop nearby, or failing that, order it from Amazon.

I will keep you up to speed in all things once I complete them.

For now? If I presume that the lower hull measured at about 29 ml is correct, just the portion of the hull's volume that is denoted by the coppered area - is roughly 93323 cubic feet in volume. If that volume is about 1/3rd the overall volume of the ship (just eyeballing it here), the ship's hull volume should likely be around 279969 cubic feet.

if I divide the above figure by the Tons Burthen that is historical for the HMS VICTORY, then each ton burthen should be about 130 to 150 cubic feet. Whether this value will hold true for the smaller ships, I'd refrain from doing so only for the following reasons:

1. How accurate is the model itself
2. how accurate was the measuring process?
3. The HMS Victory is a triple decker as far as how many gun decks it has (inclusive of the spar deck). Lesser rated ships will likely have a lesser rato of Cubic feet per displacement ton than will the HMS Victory.

Will post later if I ever figure out how to waterproof the upper assembly enough to get an approximate value in ml of water it held.

[Polydamas]

If you have or can borrow a digital kitchen scale you should be able to get it to measure in grams and use 1 g water = 1 cm3

[hal]

Here is my update on the task I set forth for myself.

Bottom half of the model contained just shy of 30 ml of water. The upper half - which included the hull above the water line, and also included those portions of the hull that were above the spar deck - measured at about 41 Ml.

At a conservative estimate of 80 ml of water total, possibly 81, the final derived volume for the hull would end up being equal to about:

3218.05 cubic feet per ml or in round numbers, roughly 3,218 cubic feet per ml.

At that rate, the Overall target volume for the HMS Victory should be about 257,000 to 260,000 cubic feet. At a listed 2142 tons burthen, that works out to roughly 120 cubic feet per ton burthen.

Eventually, I may try my hand at trying to create an HMS Victory Analog using GURPS VEHICLES 2nd edition - and substituting real data for analog data such as weight of cannons, etc.

[mlangsdorf]

Originally Posted by hal

that works out to roughly 120 cubic feet per ton burthen.

120 cubic feet of water weighs nearly 4 tons. I know tons burthen was a builder's formula and not a measure of displacement, but I'm not sure if I think it's reasonable that the nominal cargo load was 25% of mass or if that feels grossly off.

[Rupert]

Originally Posted by mlangsdorf

120 cubic feet of water weighs nearly 4 tons. I know tons burthen was a builder's formula and not a measure of displacement, but I'm not sure if I think it's reasonable that the nominal cargo load was 25% of mass or if that feels grossly off.

The rule of thumb was 100 cubic feet per ton of cargo, so it's not too far off, and probably reasonable for the total volume of a warship.

[hal]

I'm going to re-iterate a warning with regards to this experiment with water displacement within the model and the real world as well as the GURPS VEHICLES rules...

1. The formulas for determining the hull weight etc may not be all too realistic (or they may be pretty darn close!) I just don't know
2. This was intended to try and figure out what would be a close reasonable approximation for how much volume the warship itself has before you add things like ballast, supplies, materials for repairs, shot and powder, hammocks for sleeping quarters, along with outright volume/mass taken by the weapons carried aboard ship.
3. This was for a three decker warship, not a frigate, nor older style ship of the line battleships. It certainly will not apply to the 17th century ships with their high forecastles etc.

In the end, if I can ever find an age of sail ship model kit for say, a Brigantine or a Pink, or a sloop of war - I may (if the model is cheap enough) give that a try as well (ie measure the water the hull holds). I came across an old model at a store the other day for the USS Constitution - for about $23 (the box was beat up). One model I really wish I could find as a plastic model is the Boston built Rattlesnake (Circa 1779 - launched 1781) that was eventually captured by the English Navy and used as a sloop of war (essentially about 200 tons burthen). Ah well, I've enough to keep me occupied these days. I still want to get my Black Seas models built and rigged so I can use them for table top gaming with a buddy of mine.