Problems with GURPS and Age of Nelson stuff

[hal]

Originally Posted by Anaraxes

Perhaps not wise. The hull of HMS Victory was two feet thick at the waterline. Going by the progression on B558, this gives the hull DR 24 and 66 HP per ten square feet of area. Given that it's a purpose-built warship and not just a tree trunk or simple slab of wood, but braced, you might justify even more DR.

If you take that 6Dx5 literally, and roll 6D five times, rather than summing them, the 12-pdr mostly just bounces off unless it gets lucky. Old Ironsides indeed. Not RAW, but a curious observation that struck me.

Calling a side 190 feet (gun deck, less than overall) x 30 feet (draft) gives 5700 sq ft, or 570 * 66 = 37,620 HP to utterly destroy the hull. She'd sink well before this point, of course.

And therein lies the $64,000 question:

Why is it, that the one set of rules for GURPS quotes a given set of HP ranges based upon the entire weight of the vessel, and then quote another set of guidelines for "walls" of a given size - which ends up granting a higher rate of Hit points? The equation that the whole is equal to the sum of its parts doesn't seem to hold here.

As for the statistic of the width of the hull at the waterline etc...

I took the time to purchase two separate books on the hull construction methods of warships. One is titled "THE ANATOMY OF NELSON'S SHIPS" while the other is titled "The Construction and Fitting of the English Man of War: 1650-1850". Both books give an idea of how those pieces of wood are fitted together, along with why certain types of tree parts were used for various fittings within the hull's frame. In and of itself, a cannon ball travelling through the wood, would have to bypass its actual DR, then chew out pieces of wood, travel through empty air (or not - having a crewmember lose his arm without apparent cause from a travelling cannon ball isn't a particularly fun way to be wounded to be sure!) - and then exiting out the other side - doesn't neccessarily impart all of its potential energy into the ship outright. Then there are the statistics where a given cannon ball can penetrate through a given distance of oak. Those ship's were TOUGH. Question is - why doesn't the current set of rules give that level of toughness to the ships outright?

Grabbing GURPS FANTASY page 142, the spanish galleon has a hit point value of 680, and a DR of - are you ready for this? DR 15. An 18 lbr in GURPS FANTASY does 6dx4, or 80 points of damage on average. Number of shots to take a Spanish Galleon down to zero hit points is 680/(80-15) or 10.46 shots. The number required to take it to -HP is a mere 21 hits.

Now for the fun part...

In terms of equivalancies - a modern house (ie a frame house) has a hp value of 580, and a DR of 6. A wooden ship would be capable of being at least three times the size of a modern house, contain far more lumber than a frame house, and yet - the house has 85% of the hit points that a Spanish Galleon has.

Part and parcel with the problem I think, is the presumption that the hit points scale upwards at the cube root of its weight.

Case in point:

An object that weighs 1000 lbs, made entirely of wood, would have a hit point total of 1000^(1/3) (ie cube root) x 8, or 80 hit points. A 3,000 lb object made of the same wood, would have a hit point total of 115. A 3 fold increase in mass but only a 1.44 fold increase in hit points. A four-fold increase in mass will result in only a 1.58 fold increase in hit points.

That same progression does NOT hold true when firing at a simple wall. A two fold increase in surface area (and thus a two fold increase in mass) results in a 2 fold increase in hit points.

As for the IRONSIDES observation...

I would agree with you as to the fact that the seeming bouncing off the hull by the cannon balls would seem to indicate that the USS CONSTITUTION (or old Ironsides) had a higher DR than might be expected, but if you look HERE at the loadout of the ship firing at the USS CONSTITION, you'd find that her normal complement of long guns (ie non-carronades) was no heavier than 18 lbs. 80 points of damage on average, would not be fazed by a mere say, 20 points of DR. Even at ranges longer than 1/2 damage, average damage is 40 points, of which after 20 points of DR is subtracted, you'd end up with 20 points of damage. In truth, I don't think I'd make the USS CONSTIUTION's DR value all too high simply because I don't think the legend is true. But, be as that may be, I do think that GURPS needs to look more closely at the concepts of how Hit points are determined.

What I really need to do, is relearn how to use the GURPS VEHICLE DESIGNER program and try to build analogs of ships as best as I can. I tend to utilize a volume of hullspace equal to 70 cubic feet per Tuns burthen. That being the case, I suspect that the HMS VICTORY, were I to try and build it using GVD, would be made with a hull of 151,340 cubic feet.

[Anaraxes]

one set of rules ... and then quote another set of guidelines

Not that it solves the problem at hand, but the two rules cover two different things. The "death" of an object isn't necessarily its complete destruction. The wall rules give you a ten square foot hole in a wall. The larger number I calculated would make a ten square foot hole over every ten square feet of the hull -- that is, eliminate it to the last splinter. The ship would "die" long before that point. Even one ten square foot hole under the waterline would do it.

You're going to more than just hit points anyway -- hit locations at a minimum. What's a Hornblower / Aubrey battle without aiming at the masts and yards, or the crew, or the hull, as the case may call for?

[Agramer]

Just a note:

Ships of the line were extensively reinforced.

There was "code of conduct" that SOL didnt start shooting at Frigates first,unless Frigate started attack since that was "unsportsmanlike".

And considering Frigates were 30ish cannon ships,which puts them at 30-50% of SOL broadside reason cant be only broadside size,since than they would have much bigger impact in battles instead of acting as "observers" in "every" documented SOL vs SOL battle.There must be substantial differences in hull strength/endurance coupled with size of cannons.

There was only one case of Frigates defeating SOL,that I know of, and that was action fought by coast of Ireland between 2 British Frigates and French SOL. Weather was heavy and French SOL had design quirk that set his lower ports 50 cm lower than was usual so it couldnt open lower gunports during battle.
One of frigates ,was actually "shaven off" SOL(upper deck cut off to give ship more speed),which was biggest frigate at the time.
Only "shaven" SOL frigate "survived" battle.

I cant recall name of battle,but it is considered one of greatest moments in British seamanship naval history.


Also,from what I recall of seeing at seaside of wooden ships,they all have 1 inch(or thereoff) thin planks on hull. So maybe Merchant ships were much different in build than warships.

And warships(Frigate and so 4th-6th rate) were much more fragile in build than Ships of the line.

Sorry for not addressing any of issues you asked for :(

[hal]

Originally Posted by Agramer

Also,from what I recall of seeing at seaside of wooden ships,they all have 1 inch(or thereoff) thin planks on hull. So maybe Merchant ships were much different in build than warships.

And warships(Frigate and so 4th-6th rate) were much more fragile in build than Ships of the line.

Sorry for not addressing any of issues you asked for :(

Not to worry - as far as addressing the issue <g>. The problem overall is the fact that the current vehicle rules for GURPS seems to imply certain things are possible, whereas the historical evidence seems to imply the opposite. In the example I gave earlier of a frigate like ship firing upon a "Mystery ship" whose displacement tonnnage was about 3000 tons - was done to illustrate a point. Get the real world data of the ship's mass/weight - take the cube root, multiply by 8 to derive its total hit points. Then utilize ONLY the firepower of a frigate, and then illustrate just how atypical the results of combat were, by finally displaying what precisely was the mystery ship. There is just NO way, that the HMS VICTORY could be brought to within near sinking situation by 3 salvos of broadsides from a mere frigate's armaments. Even a French Second Rate's armaments would be sufficient to sink the HMS VICTORY - which, historically weathered the battle of the Nile for far LONGER periods of time - let alone what it endured at Copenhagon.

For what it is worth, the British generally were able to inflict two broadsides in the same time that their opponents could loose off 1 broadside (as far as reload times) simply because they were better trained. Their seamanship permitted them the ability to perform duties such as tacking across the bow instead of having to wear across the stern. Their ships were kept in better repair simply because they had access to raw materials more than did the French and/or Spanish as a result of the blockade. Reading about how desperate things became for the French as they attempted to land an invasion force in Ireland only emphasized the point that in some cases, the French poorly provisioned their ships in the way of foodstuffs - forcing them to turn back when the food ran out.

In any event, I'm concerned that GURPS rules in GURPS 4e make the ships less capable of surviving a sea battle than is historical, but I'm sort of helpless on how to fix the problem. This is one reason why I really SHOULD try and determine how GURPS 3e handled it to see if it is better or worse than GURPS 4e.

[lexington]

You know ships are Unliving rather than Homogeneus (the stats on B464 back this up). Of course this only makes things worse.

[Kromm]

A few things to consider:

• Hard wood affords DR 1 per inch. Reinforcement (cribwork, lamination, etc.) can add from 10% to 20% to this.
• Compartmentalization and other decent construction options can boost a ship's HP by 10% to 20%, too, and also add up to +2 to its HT.
• Tall ships are Homogenous, which means not only that they use the superior column on the Object Hit Points Table, but that guns – which are piercing – have a wounding modifier between ×1/2 and ×1/10 (p. B380).
• Later design rules might well add further construction options with interesting effects, such even higher DR, HP, and HT, and Injury Tolerance (Damage Reduction) vs. certain damage types.

It's ill-advised to try to compare GURPS Fourth Edition to GURPS Third Edition here until GURPS Vehicle Design is released. GURPS Low-Tech and GURPS High-Tech only present smallish, PC-sized vehicles. The big stuff requires design rules that don't exist yet.

[David Johnston2]

Originally Posted by hal

Now for the next problem - GURPS rules for damage to inanimate objects and determining how many hitpoints vehicles have based on the rules on page 558 of GURPS CAMPAIGNS.

In theory, a ship that displaces 3,000 tons, weighs about 3,000 tons. So, lets see how many hitpoints such a ship weighing 3,000 tons would have.

3000 x 2000 = 6,000,000

The cube root of this is: 181.7120593

Multiplied by 8 for an Homogenous object, and we have a final hit point total for our ship at:

1453.696474

Lets be nice and round it to 1454 hit points and call it done.

Now, lets use a 12 lbr cannon listed from GURPS HIGH TECH. .

Wrong source book, perhaps. They were after all, using cannon indistinguishable from the TL 4 ones for quite some time. That being said, there's no way you were going to hit with 83% of your shots with a typical crew.

[hal]

Originally Posted by David Johnston2

Wrong source book, perhaps. They were after all, using cannon indistinguishable from the TL 4 ones for quite some time. That being said, there's no way you were going to hit with 83% of your shots with a typical crew.

Skill 12 crew

at a range of 20 yards, -6

Cannon accuracy: 2

Size modifier of target ship - +6 or +9 or even +10 depending upon which rules you utilize to get the size modifier for the HMS VICTORY. See this thread HERE.



Final to hit number (sans any situation modifiers such as long term aim, sea state, fog obscurement, etc) using the more conservative SM of +6, we get:

12 + 6 - 6 +2 or 14

Per page 171 of GURPS CHARACTERS, a skill of 14 equates to a probatility of 90% chance of success.

Now, if we're going to go with a FRENCH crew, with SOME training, just not up to the standards of the British at that time, we're looking at maybe a skill range of 9 - 11, or call it a skill 10 for average.

That drops the final to hit from a base 14 as above, to a base 12, which has a success chance per page 171, of 74%

Note that I did NOT use the +9 size modifier or the +10 Size modifier for the HMS VICTORY, nor did I include the extra +2 bonus for aiming that can be gained by taking one's time to aim at the ship instead of firing immediately upon taking minimal time to aim (getting only the weapon's accuracy bonus).

[Turhan's Bey Company]

It's a bit tangential to all of this, but I wonder if massed fire (archers in massed combat, ship broadsides, Napoleonic and Civil War troops) shouldn't, for ease of resolution, use the rules for rapid fire weapons.

[Kromm]

Originally Posted by David Johnston2

That being said, there's no way you were going to hit with 83% of your shots with a typical crew.

This is important, too. Modern-day gun crews – with radar, ballistic computers, etc. – consider themselves lucky to beat 50% under fire. Without all that lettuce, hit rates will be much lower. I've read of estimates below 25% for black-powder guns, and quotes to the effect that even at close range, a 1-in-3 hit rate (33%) was a WWII-era achievement.

GURPS seems to back this up. Take your skill-12 "professional" crew, add Acc 2 for typical armament, tack on another +8 for target SM, and you have skill 22. Then you factor in -2 for "dodging" (unless you're just sitting there, letting them pound you), -1 or -2 for a carriage-mounted weapon from a water vehicle (depending on seas), and from -7 to -13 for 30 to 300 yards (typical range bracket), and you're at skill 5 to 12. That's a hit rate of 4.6% to 74.1% before factoring in enemy movement – the dodge I mentioned, which both sides get. Assuming skill 12 for that, too, the vehicular Dodge roll is 9, so final hit percentages are 2.9% (rough seas and long range) to 46% (calm seas and point-blank range). Crummy skill-10 crews would reduce attack rolls to 3 to 10, and Dodge rolls to 8, for 0.4% to 37% hits. You could probably fairly take the average here and go with ~22% hits.

Alternatively, treat it as rapid fire. With +4 to hit for RoF 18, skill would be 9 to 16 for a good crew and 7 to 14 for a crummy one. Assuming average rolling, and going with Rcl 1 for totally independent guns, that's 0 hits in the worst case to 5-6 hits for the good crew or 3-4 for the bad. Out of 18 guns, that's 27.8-33.3% or 18.8-22.2%. That averages ~25%, which is a little better but no 83%.

It's absolutely critical not to ignore the penalties for your ship moving (the -2 for having a Dodge roll), and the seas prior to invention of stabilization (-1 or -2), and the effects of their ship moving (its Dodge roll). It's also a good idea not to assume ridiculously short ranges, as in the movies. These guns were proofed for 1,000 yards and used at 30-300 yards. The test of a ship's crew was how gutsy they'd be . . . some captains fired at hundreds of yards, others at tens of yards.