Forum > Paddlewheels (Large)

Stability

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Eddy Matthews:

--- Quote from: "thewharfonline" ---I was always lead to believe wheels made the boat more stable on the side...I don't know if this is only rumour though.
--- End quote ---


Exactly the oppossite Sean! The paddlewheels etc add no extra floatation, only a large amount of weight hanging on each side.... Try sitting two people in the centre of your boat - Nice and stable yes? Now move the two people so that one is sitting on each side of the boat - Nowhere near as stable then is it?

This is exactly what happens when you add paddlewheels, sponsons and paddleboxes... You DECREASE the boats stability!

Ask anyone who has modelled a sidewheeler, and most of them at one time or another will have made a model which was totally unstable, or at the very least tended to dig a paddle into the water on a turn - Even when you straighten the boat up the paddlewheel stays dug in and the boat runs with a frightening list to one side or the other!

Yet another thing to think about!

One final point - my posts are intended purely to HELP with your builds, not to put you off in any way. Yes small paddlers can be made to work, but they need careful planning and a lot of thought to be successful. Trial and error is okay to a point, but the basics must be right (or nearly right) in the first place or you are doomed to failure. Hopefully if some of the major pitfalls are pointed out you can avoid some of the issues that many of us modellers have experienced!

Sean Bryan:
And the pitfalls that we discover we can write about and stop other paddler builders making the same mistake!

Attached is a photo to show the effects of bad and prove that even the big boats can do it. It's dark because of the sailpast buts it's PS Alexander Arbuthnot with everyone standing on the side of the boat that already has a room full of tools on the side....

Don't worry Eddy I'm not taking your posts as being disheartening! This advice is needed...especially for first timers like myself. And if advice isn't taken...well just take a look at Lady Rae! Michael...a photo perhaps?

Roderick Smith:
Without any proof, I don't think that the proposals for Grebe or SJ will make either unstable, and certainly not in the calm waters in which they will be used.

Sean's photo of AA listing are interesting, but presumably well within stability limits (the thumbnail is black, but clicking to bring up the photo in full reveals the image).

A Sydney twin-deck screw ferry did capsize when everybody rushed to one side during a regatta or watching something famous.  IIRC the era was the 1930s, and the vessel was one of the R fleet (Rodney? Radar?).

PS Ruby was a lean greyhound.  There are published references to crew members rolling barrels of water from side to side to enhance stability around curves.  The current restoration has put only the wheelhouse back on the third deck, and not the cabins or music room.  AFAIK this is to provide stability to meet modern survey requirements.

The small PV Eliza something has two decks on a short hull.  It wears outrigger floats (like training wheels on a child's bicycle) to enhance stability.

We may laugh at PV Lady Rae being overbodied, but is it unstable?

I often ponder that PV Shiralee looks top heavy (two decks on a short hull), but that doesn'ty prove that it is top heavy.  I was cruising alongside for half an hour in July, it it wasn't listing.  I did draw a design at the time which recessed the lower deck into the hull.

Photos of all of these vessels will appear in the discussion thread in this forum in due course.

Regards,
Roderick B Smith
Rail News Victoria Editor.

Sean Bryan:
Lady Rae rocks from side to side and sits in a list and now has outrigger pontoons to support her I believe...unstable I believe.

Consider PS Ellen. There were reports after lengthening that upon turning a bend she would list so much that the skipper could get a cup of water from the river (of course the river was obviously cleaner back then!) I've seen photos of Ellen...I can understand where these stories come from...her size is impressive but definately wasted.

Many steam launches carry their boiler in the front of the boat...does this assist stability...I would assume so...but I would also assume then that the quite a few people are required to sit in the stern of the vessel to balance it out...my thoughts on launches.

paddlesteamerman1:
Also the PS Marion, I have cruised on it several times now, and it as nearly always on a list to left (unless you were lodged on a sandbar at Goolwa like we were and getting towed off by the Oscar W). Always there is one paddle deeper than the other... But I wouldnt call the Marion unstable.. It would catch a lot of that howling wind down the long wide straights of the Murray in SA and it has proved stable.
Sean, that is a great photo of the AA on its classic list, I also have a few of it on a list!!
Do paddles ALWAYS decrease the stability of a vessel? Or just sometimes?
With the SJ Hull being nearly (half as wide as she is long) 6' wide and only being 14' long, it is a stable boat, and was used to row out to ships back in the 20's on the rough Southern Sea at Portland...
And paddles are the same both sides, so on flat water does it decreased the stability or is only when the boat is getting pitched around on small waves and one side goes up with a wave and the other down that the boat goes over or under???

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