for Deck Roll disturbance coming from a Broadside?

[Norfolk nChance]

Quick Question

Cannon recoil calculations

Anybody know the maths involved for Deck Roll disturbance coming from a Broadside? 

http://www.navweaps.com/index_tech/tech-022.php

 

Something like the above. Also, the accuracy or spread ratio effects caused from multiple decks.

 Pointers in the right direction if possible. Not Static have them already...

Thanks

 

Norfolk.

[Fluffy Fishy]

You probably won't find a distinct calculation because there are so many variables involved. The best you will likely get without a PhD in physics is looking at recoil values themselves for specific cannons taking specific loads.

The actual roll would depend on how tender the ship is, how deep or wide the hull design is, how heavily the ship is currently heeling but also the positioning of the cannons themselves and how it compares to the ballast and centre of gravity for the vessel in question.

The pulley system in place by the late 18th century also means a lot of the force is dissipated over time so it won't have a huge affect on how the ship in question would change in the water, especially when considering that guns were fired in quick succession and not all at once in a massed volley.

You could get a very basic idea from combining texts on cannons and the information contained in books like  "Seamanship in the Age of Sail: An Account of Shiphandling of the Sailing Man-O-War, 1600-1860"

The ballasting, tactics and design of ships of the line at least would easily compensate for the guns fired, this is why you dont hear many accounts of ships capsizing in battle unless sand bars or a lot of damage are involved.

Sorry this probably isn't the answer you are wanting but I hope It helps at least point you in the right direction.

[Norfolk nChance]

Thanks, @Fluffy Fishy

 

It’s sort of what I thought. @Jean Pual Vilvenue made a comment about having the Graphic’s of the guns recoiling when fired. This sounds great but without any impact on the ship I thought it was like watching a porn movie without a storyline… he laughed.

Supposed by your assumptions the big SoLs are just gun platforms and the sheer weight and pully system would negate anti roll if that’s term…?

On the smaller Frigates probably with cannon weight ratios heavier to the overall platform an effect would be assumed or am I wrong here?

Thanks for the feedback as always

 

Norfolk

[Fluffy Fishy]

Its not the case that the ship wouldn't have any effect at all, but sustained fire wouldn't really create much more of an impact that wouldn't be seen as a part of its general sailing characteristics, for example if you had, say a ship of the line who's ordinary sailing characteristics would see her heel perhaps 3 degrees and roll a further 2-3 in the waves, firing guns might create a further roll of 1-2 degrees although this would largely be compensated for by using less cloth in battle, most SOLs weren't really designed to tilt more than around 4 degrees in battle while frigates would sometimes double the numbers above.

Ships were specifically designed not to sway too much by the mid to late age of sail because too much differentiation in height made it a huge amount more difficult to keep aim, especially as most cannons of the period either operated on a system where wedges were driven between the carriage and the gun to determine height of aiming, while fancier models operated on a screw system where it would be rotated to change the vertical aim, both these systems were poor at dealing with much change in the differentiation of height.

Frigates would behave slightly differently, largely due to them having shallower drafts and their main gun deck being comparatively higher than that of a line ship, meaning shooting would have a slightly larger effect but again it would be pretty negligible.

I think what most people refer to when it comes to wanting recoil in the game is the animation of guns shooting backwards into the hull of the ship, before being reloaded and redeployed, so what you are looking at isnt the same kind of recoil you would get in say an FPS game where the gun moves around as you shoot, but a system that pushes the force backwards, if you want to see how it works its probably worth reminding yourself with a few of the battle scenes from Master and Commander, where the system of ropes and pulleys absorb the backwards motion created by the shot, but if you want to learn more about the behaviour of the ship I would certainly check out the book I mentioned earlier.

Here is the ISBN 13 number, you can get the ISBN 10 from the digits after the dash: 978-1844863099

Below is an amazon link (for the UK store)
https://www.amazon.co.uk/dp/1844863093/ref=olp_product_details?_encoding=UTF8&me=

[Odol]

The thing is about this... a real ship of this time, wouldnt have to worry about this as the cannons are not fixed to the ship.  They are aloud to move with their recoil.  That and the mass and power of the shot is not enough to move a ship of this size.  Unlike the USS Missouri or any modern Battleship, which fire more poundage per gun than the Santisima does in an entire broadside. 

[Norfolk nChance]

25 minutes ago, Fluffy Fishy said:

Here is the ISBN 13 number, you can get the ISBN 10 from the digits after the dash: 978-1844863099

Below is an amazon link (for the UK store)
https://www.amazon.co.uk/dp/1844863093/ref=olp_product_details?_encoding=UTF8&me=

Thanks Fluffy,

I have this already very good, but doesn't cover anything in terms of ballistics. I'll pick up the sailing man of war you recommend. 

 

@Odol

A very good point. 

I think I may have over complicated the process. Looking for resonance of the natural heel against the different deck discharges. 

 

thanks guys

 

[Norfolk nChance]

@Fluffy Fishy

I was thinking yesterday about speed and weight. We run at 5x or there about Real Life speed in Battle. Mainly you'd balance the boat slow it down and fire. However sometimes broadsides maybe fired at speed. Would this be the case in real life?

Not chains but full on charged. The reason for asking is the faster momentum of the ship makes it "lighter". Would the broadside have enough recoil to unstable the vessel.

Ref Seamanship AoS J. Harland

pg 44 Stability Curve and Boyd's table. Then pg 47 towards the end. Describe two 5 ton cannons with a ships roll they increase in weight up to 25%. It would be a very dangerous exercise to fire at speed. Yet this is common in NA.

I should stop thinking when drinking a French red

 

[Fluffy Fishy]

The reason battles are so fast in the game are more to do with realistic penetration and damage values, crossed with slightly faster reload speeds and much more flimsy planking, I'm not sure if you were about when they did it but the devs did try a more accurately valued patch where there were much truer values for wood strength, interestingly though although operating on values without considering various fatigues a crew would come under the cannon values aren't too far off.

When it comes to fighting battles, it wasn't often the case that much cloth was shown, this was for all kinds of reasons, for example, it would require less crew to manage the sails leaving more for the guns, too much sails would create more instability for the ship in combat, they would limit the effectiveness of snipers in the rigging, and if things went sour it was a lot easier to unfurl sails and run than it would be to repack them, that's possibly one of the most important key differences between NA and real life situations. So fights would be fought at much slower speeds as you said, around 3-5 kns, depending on things like weather and desired tactics.

The angular difference the heel would make and the raising of the centre of gravity involved with more torque being applied to the sail would certainly be enough to cause issues with stability, but again you would see the affect giving much more punishment towards accuracy of fire before you saw anything risking a capsize, people are still rational and with most sailors being unable to swim they wouldn't risk enough force from firepower. The force over time thanks to the rope systems in place combined with the appropriate weighting of ballast, slowing of the ship compared to its full speed for fighting and the general design of the hull would almost stop this entirely

If you want to think on more practical terms, consider how water doesn't compress very easily, and if you apply a sudden impact of force it actually behaves with a lot of resistance, with high impact properties not too unlike concrete, firing a cannon would have a shock compressive force as the hull is driven into the water, the water would almost entirely resist, with the important element being the centre of gravity and balance.

Does this help answer your questions?

Edited July 5, 2017 by Fluffy Fishy

[DeRuyter]

@Fluffy Fishy Also leaving the courses set would increase the risk of the rigging catching fire. Don't forget that the animation in NA does not accurately portray how sails were set or furled. The tops'ls and t'gallants were set by raising the yards not dropping the sail and in particular with the main tops'ls it took a lot of crew to set. You hit the nail on the head though, primarily a ship set the best maneuvering sails that would require the minimum amount of crew to work in battle - spanker, fore stays' or jib, tops'ls and in light air t'gallants.

To the OP one reads more about the impact of the roll of the ship for aiming prior to firing than afterwards. I think there was some concern for recoil on the structure of the ship when firing an entire broadside (there may be a thread about this somewhere).

[maturin]

Quote

A good, stable 74 is not expected to list more than 6-7 inches (1.24 degrees) when heeled over under the pressure of full sail and close-hauled, which in a fresh or "manageable" wind should drive the ship along at 14 kms/hour.

With the lower deck 36-pdrs run out on the lee side, and the gun crews in position (the guns on the other side being secured i.e. run in, with the muzzles hard up against the ship's side, and the gunport lids fastened), the list will increase by a further 3 inches (1.38 degrees heel in total).

Another test of stability, undertaken while the vessel is at anchor, consists in running out for example all the port-side guns, gun crews at the ready, while the starboard-side guns are run in to the full extent of their breechings: the vessel should not list by more than 13-14 inches (2.5 degrees).

Quoting from Boudriot.

Arguably the effect of actually firing the guns would be greater, as these are measurements taken with all the guns at rest. But I doubt it would be by much.

I never would have imagined that 74-gunner could be so stiff.

https://ancre.fr/en/ouvrages-de-base-en/9-vaisseau-de-74-canons-1780-traite-pratique-d-art-naval-1780-en-quatre-volumes-base-de-la-collection.html

 

Put the idea of capsizing out of your mind. These ships were practically impossible to capsize without a serious storm or equivalent squall.

[maturin]

On 7/4/2017 at 2:23 PM, Norfolk nChance said:

pg 44 Stability Curve and Boyd's table. Then pg 47 towards the end. Describe two 5 ton cannons with a ships roll they increase in weight up to 25%. It would be a very dangerous exercise to fire at speed. Yet this is common in NA.

I should stop thinking when drinking a French red

 

You're reading things that refer to very different dynamics here.

Boyd's table on page 44 refers to longitudinal stability, not transverse stability. Bows sinking and sterns rising. Not listing to port or starboard.

The example on Page 47 refers to a scenario where the stability of the ship remains the same regardless of where the guns are situated. The 25% increase refers to the guns' helpful ability to reduce rolling in waves (and it's actually more of a 5% increase, 25% vs 20%).