# Modern Hi Tech Viking Ship Development Class

Discussion in 'Boat Design' started by Johan Strydom, Jan 23, 2021.

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1. Joined: Jan 2021
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### Johan StrydomJunior Member

Sorry Bluebell I missed your first post. This is an idea that if the real calculations, and not opinions work out, maybe somebody with the skills to implement it, might notice it. I am playing Jules Verne. Hi-Tech materials as in Carbon Fiber etc. I have no CAD skills. I have not found the need to draw it, yet. I imagine a giant sea kayak with a domed deck, everybody inside. There can be a half transparent tube down the center for extra headroom, lookout, providing light inside. Sections can be made to slide open. There can be a passage down the center of the boat where the headroom is the highest. Either side of the passage the floor can be raised for storage under. There can be two shafts running the length of the boat either side of the passage. Each side can have a double row of recumbent pedalers, facing each other in a staggered pattern. The rotation plane of the axle and chain wheel will be the same. The removable bunks can be above the pedalers. My numbers are suggestions. A bigger boat will have much more carrying capacity compared to hull surface area? I see a racing 8 can reach 12 knots, which is above hull speed. That is possible because of the length to beam ratio? So if the beam is increased to enable two rowers side by side that advantage will be lost? And the surface area resistance might increase more than the extra power? The trireme reached 9 knots. Hull speed for 80' boat is just under 12 knots. At 10 knots a voyage from Norway to Iceland will take 3 days. I see a racing 8 is 65' long. I did not realize that. So in 80' you can fit in 10 sliding seat rowers? Will a racing 8 fitted with a Mylar fairing over the rowers go faster upwind? What is the difference in power output between a sliding seat rower and a recumbent pedaler? The pedalers power output is continuous, unlike the rower. A smaller boat will have to be open I think. Bajansailor thank you for all the links. Bluebell did I miss any questions?

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### Johan StrydomJunior Member

I watch those videos all the time. Thank you. They are amazing.

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### Johan StrydomJunior Member

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Rowing vs. cycling is not about raw power of the human, but how much of that power can be transmitted to the water as propulsive force. An optimised screw is better than an oar (especially with waves), but to get the the oars maneuverability you need at least two screws.
Lenght to beam ratios of war galleys ranged from 6:1 to 10:1. "Row assist" boats were 4:1-6:1. L:B ratio for exceeding hull speed in displacement mode is around 8:1. The L:B ratio has to balanced against stability and displacement. Plenty of galleys only had minimal ballast and minimal carrying capacity, they relied on shoreside stops for food and water, and those were as frequent as every night. Freeboard is the next constrain, the oars have to be close to the water, wich does not go well with high waves and minimal stability.
Fixed seat rowing is limited to around 10kn boat speed, there is no space for sliding seat rowing on a big boat. Rowing strategies were: one man per oar and bench, several men per bench serving one oar, and three men per bench with individual oars. Rowers slept on their benches, there are no bunks.
Average speed under oars was 2-3 knots depending on the sea state. Ancient war galleys could sustain more, around 4kn, but those are the kind that stopped every night for food, water and rest. Max. speed can be as high as 10kn, but it can not be sustained for more then half an hour, and the crew is exhausted afterwards. A typical shift on the oars would be 2 hours.

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### BlueBell"Whatever..."

SD,
You missed more than my first post.
Good luck.
BB

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### bajansailorMarine Surveyor

Reading Johan's post #16 above somehow reminded me of this film scene from Ben Hur -

What is your budget for this project Johan? Or will you be inviting the rowing slaves (sorry, partners) to stump up their shares?
Who is going to be banging the drum to keep everybody in sync?

Yes - the beam of a rowing 8 is probably no more than about 18", so you have a L/B ratio of around 40 - a far cry from the stereotypical average for displacement boats of around 3 - 4.

The only way that your trireme / galley / whatever is going to do 10 knots on passage from Norway to Iceland is if you put an efficient sailing rig on it, and have good weather routing / planning - or install a suitably sized engine.
Even the Roman slaves in Ben Hur would not be able to keep up with a sailing rig - and how they must have dreamt longingly for iron topsails!

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### Squidly-DiddlySenior Member

AFAIK no Vikings (or anyone else) ever rowed any real distances. Rowing a longboat was only for the amphibious assault landing phase to get up an inlet before the defense could be readied.
Not sure if today's trans-ocean rowers are actually rowing across or rowing while the boat catches some wind and current.

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### Squidly-DiddlySenior Member

I always thought I might be handy to run a long notched stick over (or under) the oars to keep them in sync with less skill. It would be notched and each oar would tied with just enough play in the tie to keep it in the notch but not bind the rope. That way the rowers wouldn't need to be all the same strength, but how would you know who was slacking?

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### Johan StrydomJunior Member

I apologize that I did not mention it in my first post that I do not intend implementing this idea. Thank you all for all the information and opinion provided. This is my first post, I am learning.
This idea to take the concept of a Viking ship and develop it in modern context, after the discussion so far, yes Bluebell I am aware that I missed much, It can take two directions. The purpose of a Viking ship was the fast transport warriors. Propulsion was by square sail. Oars was used for landing and departing and passage along rivers. To justify the large crew, it ends as a spartan passenger boat, with accommodations like a back packers. Modern easily handled rig, and a catamaran hull.

If I want a human powered racer, the race can be a 7 stage race with average time for each stage of no more than 4 hours. As a development class boat I can think of two possibilities. Limit the number of grunts, and everything else is open, except that it must be seaworthy. The second can be to limit the length of the boat, and leave everything else open, as long as it is seaworthy.

Squidly-Didly, I thought of a rowing system where the seat stays stationary, but the rowlocks move. the rowlocks can be on a bar so that they all move at the same speed. If a pulley system is used the direction of the rowlock movement can be reversed. this will allow the rower to face fore ward. The oars will stay at 90 degrees to the hull throughout the stroke. This will make the blades more effective. Less power will be needed to move the rowlocks instead of the seat and the weight of the rower. The momentum of the rower, and oar will stay the same as that of the boat, and do not change the whole time as in a sliding seat system. I think the constant change in momentum must require a lot of power. The fore and aft rocking of the boat will also be reduced. Dudley Dix says that the moving rowlock system have been done before. I would like to believe that my pulley system is original.

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### gonzoSenior Member

That is not correct. The vast majority of the Viking ships were built for commerce. Further, even warships had to transport loot and slaves.

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### Johan StrydomJunior Member

You are right, the cargo ships was for cargo. The warships was designed to be fast and carry people. I translate warriors and slaves as passengers, Loot as shopping. Another translation is fast into racing. I can not ad anything to racing sailboats, but I think human powered boats leave room for exploring. It is not clear to me why that can not be scaled up. The speed record is held by a single person power boat. How would you translate a Viking warship?

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### gonzoSenior Member

It is simple. Scaling increases displacement by the cube, but the surface by the square. That means that doubling the length of a boat will increase its displacement by the square of the surface area. Scaling a boat up will not have enough surface area for the crew and oars compared to a rowing shell which you used as an example. However, humans do no scale.

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### ReubyNew Member

Have you come across Bantry Bay gigs and Atlantic Challenge International? They are 38', 3 mast, 10 oared boats that compete in sailing/rowing/seamanship contests including passage racing.
I know its not quite what you are thinking about but they are probably the closest thing that exists. I have often thought I would love to do a longer multi day passage race in them, and have also spend many hours wondering about what a modern day equivalent could be like.

Atlantic Challenge International https://www.atlanticchallenge.org/

Atlantic Challenge Great Britain https://atlanticchallengegb.org/

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### Johan StrydomJunior Member

Thank you Gonzo. I am aware that the volume increase faster. I thought that was an advantage because you can ad more grunts, but I see that the resistance increases faster too. By surface area do you mean floor or deck area? I think I understand.

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### BlueBell"Whatever..."

I have pictures of this boat but can't find them.
Here, however, is a link:

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