Ullman Seats - Page 2

RibRoy · 01 March 2005, 20:42

What a response !
I will be talking to Henrik at Ullmans tomorrow. Shall give him a link to this thread, maybe he will have some comments to your theories Tim.

Hopefully the boat will be delivered in Norway first of April.
Will post a report after some serious testing.

Regarding the holes in the springsystem, guess I have to throw away my Bermudashorts and go for tight underware : )

Regards
Roy

robin · 01 March 2005, 20:43

If money were no object then a set of seats that would stop the bonecrunchingheadwobblingarseachingteethcrunchingn eckcracking 'whoops I timed that one wrong', and if these seats are the ones to stop it...excellent I will have some.
They look the mutts anyway so why not.
No worse than having an 'a' frame to hang a couple of lights on is it?
I want 2 of them but they would double the weight of my boat!! arf

jwalker · 01 March 2005, 20:43

Ah, Slimtim I see what you are getting at. You mean the direction you feel the hull would move is not directly inline with the centre of the spring/damper? If so, it does not matter because the seat fulcrum will move upwards in that direction since it is directly connected to the hull, thus the spring will compress.

jwalker · 01 March 2005, 20:50

To move on a bit, I'm surprised at the lack of rib seating which has good lumbar support. Essential to keep that lordosis ya know.

slimtim · 01 March 2005, 20:58

Richard, it probably would've been if I had thought of it! Instead I'm investigating manufacturing techniques for advanced composite wings...still quite interesting though.

Jeff, Good point about the wheel barrow. However the bit about the movement not being in line with the shock centre line is not what I'm on about...sorry! The forks are just an example. Mountain bike designers generally try and get the rear wheel to match the path of the front, but this obviously doesn't require the wheel axle movement to be in the same line as the shock stroke. Clever linkages and Virtual Pivot Point designs (I won't get into that!) help to acheive this.

I'm trying to think of a better way to explain myself. Perhaps imagine the force from a wave being "transmitted" into the hull and then up that linkage straight into the helmsman's arse. If the linkage was the other way, this force would cause the hull to move upwards more freely and the energy would be converted to heat in shock damper system instead of movement in the helmsman.

Robin, get some for the new boat! You'll be able to cruise along taking pictures when its rough!

RibRoy, Would love to hear Henrik's opinions on this. Sorry again for thread hijack, I've PMed JK to see if he'll split it.

Cheers

Tim

robin · 01 March 2005, 20:59

I would imagine that back injury or just discomfort from slamming along in chop is sometimes enough to put some people off ribbing/powerboating completely. I know I am 3 cm shorter than I was 10 years ago but thats probably just age!!!

swginn · 01 March 2005, 21:02

Tim I understand what you are on about but I think you are looking at this the wrong way. The seats are designed to mitigate shock and you have to look at how the load (the weight of the person sitting on the seat) is applied to the seat and not the relative movement of the boat under the seat.

Nick already made the point that as the bow comes up you are shoved back and down onto the spring exerting a load acting parallel to the spring (compressing). If the seats were the other way around you would exert a load acting perpendicular to the spring (exerting a shear force but very little compressive force)

The way you are looking at the problem is as if the boat is exerting the load on the shock absorber and causing it to compress, however it is not the case. If there was nobody sitting on the seats while underway they would only compress slightly (under their own weight). However they will compress properly when loaded with the weight of a body. This shows that it is your own weight that causes the shock.

Another reason for the setup like this is that you are pulled slightly away from the console in the event of a stuff/ hard landing/ ploughing into a big one!! Otherwise you would be flung towards the console!!

Sorry to everybody that I have confused even more!!

slimtim · 01 March 2005, 21:24

Steve,

I agree totally about having to have the driver on the seat to make it work. For bikes, this is known as sag and is usually set to about 1 third of the total travel on medium - long travel bikes like mine.

Also the bit about being pulled away from the console for safety makes sense (although it would hardly be noticable), but then again you wouldn't want to be pulled away from the throttle

!

I'm going to have to design my own suspended seat I think, then I can see for myself if I'm right or wrong...cos its making my head hurt now.

If the seats worked perfectly and were 100% efficient (obviously impossible), the helmsman would sit on the seat and wouldn't move in relation to the earth (assume a small see so the shock doesn't bottom out). The hull would move underneath and, in an ideal world would be free to move however it pleased. If the suspension system restricts this natural movement, energy will be transfered to the helmsman (not good), instead of being absorbed into the shock (which is what is wanted).

This is an interesting discussion.

Tim

jwalker · 01 March 2005, 23:18

....but if the seat absorbed all the energy the damper would likely get more than a bit hot.

slimtim · 01 March 2005, 23:59

Quote:

Originally Posted by jwalker

....but if the seat absorbed all the energy the damper would likely get more than a bit hot.

Bum warmer?

smokie · 02 March 2005, 03:40

RibRoy, much are you paying for the seats?

What colors can you get them in?

RibRoy · 02 March 2005, 08:45

Just talked to Henrik at Ullmanns, sending him a link to this thread now.
Maybe he will enlighten us regarding theories, colours and price.

Scary Des · 02 March 2005, 09:46

Quote:

Originally Posted by slimtim

....If the seats worked perfectly and were 100% efficient (obviously impossible), the helmsman would sit on the seat and wouldn't move in relation to the earth ......

Tim

I don’t think this is the case because if you consider how little real movement there is in a suspentions system even a little ripple would exceed the suspension envelope. Idea suspension absorbs the peak movements while slowly moving the suspended body to the new position, In effect it is a hysteresis system.

Having said that I still don’t really understand what you are saying, is your concern that the seats’ movement describes the wrong arc

With regards to the shock heating up I think fitting a transmission shower would solve that problem although it might make the boat a bit wet

Des

Alan · 02 March 2005, 12:27

Quote:

Originally Posted by robin

I would imagine that back injury or just discomfort from slamming along in chop is sometimes enough to put some people off ribbing/powerboating completely. I know I am 3 cm shorter than I was 10 years ago but thats probably just age!!!

Absolutely. I sold my RIB because of a back injury, a decision that I have regretted ever since but it went to a good set of owners

I slipped a disc back in 2002, not through ribbing but really cocked it again by going out too soon afterwards. Without being melodramatic once you have a lower back injury, you are never ever the same again (oh the constant pain!

) and its certainly made me more circumspect about what I will put myself through again.

The subject of a solution to back stress/injury on fast powerboats (be they RIBS or anything else) is thus dear to my heart! The Ullman seats look like an elegant (although I suspect expensive) solution but am very interested in feedback on them. The Stidd mission seats that JK has represent the dogs danglies of suspension seating but are priced more than the value of a decent rib. Another solution I have seen referenced in the US is http://www.glyde-ryde.com which might be worth a look. Anyone with some really old back (no pun intended) issues of RIB Int. might dig out the article by a guy called Chris Hough around 1999 about the suspension bucket seats he designed and installed in a 6m Flatacraft with 150 Merc racing engine. I drove this boat and it was fantastic, think its in Scotland somewhere now. Chris developed a mark2 version of his seat (uses a motorcycle shock absorber) which is installed on his 8.1m Scorp. He lives in the US now and I do hope to get down to see him sometime and have a play in his boat. (New Orleans is a bit warmer than Canada!). I asked Chris at the time whether he was ever going to put his design into production but he felt that the engineering involved would make the price prohibitive. (Also he had a day job anyway.)

The other solution for fast powerboats much favoured in the US is standing up either using a leaning post or bolsters. http://www.bolsters.com/index.html being the mutts nuts here. The other interesting area is in shock absorbing flooring or mats. I wonder whether this is an easy and cheap thing to apply to RIBS. There are various products around such as reviewed here http://www.tackletour.com/reviewfootcush.html

It takes a lot to beat the 'ol jockey seat though for a low cost solution. I can't understand why anyone who does any serious ribbin would have one of those nasty benchseat things. Makes by backache just thinking about it!

vortex · 02 March 2005, 12:37

Gentlemen,
Not wanting to make a long story boring but the movement range of the Ullman seat is mimicking the effect of the body absorbing an impact without a suspension seat. The link is parallel to the upper leg and the pivot is next to the knee. Thus as you bend your legs to mitigate the shock the arc of your arse goes down and back. Simple.

For an example of this natural motion have a look at National Hunt jockeys at full tilt. Enough of the pyhsics.

How much are the seats and where can they be purchased?

Mark

RibRoy · 02 March 2005, 15:14

I think you must order the seats from Ullman direct :
http://php.ullmans.com/?id=0

They cost a lot, but so does a broken back. I guess they cost about 3 times a std. jockey seat.
Probably spend some 300 hours a season at sea, so if the seats works I guess it's a good investment.

Is it anyone at the forum that work on, or know anyone that work on Tornado ? I would like to have some contact with whoever that is doing the last fittings on the boat. Sendt a mail directly to factory, but no answer yet.

Regards

Roy

swginn · 02 March 2005, 16:16

If you contact Laurence Lock at Barnet Marine I'm sure he will be able to put you in contact with the factory as he is the Director of Tornado Boats. His e-mail is:

info@ribs.co.uk

The web address is:

www.ribs.co.uk

Where did you order your RIB from, direct from Tornado or from Barnet Marine?

RibRoy · 02 March 2005, 16:35

Thanks for the tip.

I ordered it from the Norwegian importer. He is also my contact to the factory, but I would like to have a direct contact with the persons that worked on my boat if that was possible.

Regards

Roy

gtflash · 02 March 2005, 18:00

Quote:

Originally Posted by robin

There is only one alternative......fit these instead

these are not far off ideal, with a little lateral stability through floating mechanisms you could effectively have no permenant mechanical contact with the boat..

Nauti Buoy · 04 March 2005, 20:38

These look a bit familiar Rib Roy, guess this is how yours will look when installed