Suspension Seat Height / Ergonomics

[GuyC]

Dear All

In a moment of madness I've bought some suspension seats.

From a look on line the recommended seat height tends to be between 700mm and 800mm from the deck.

What drives this dimension? I'm assuming that person height or probably their inside leg measurement is the key but what is the relationship between the two? Seat height 50mm less than inside leg measurement for example.

I appreciate that there are other aspects in play as well - reach to the wheel and throttle as well.

I've got the opportunity to make the pedestals so height, distance from the console etc is all up for grabs so if anyone has any advice or information, I'd be very grateful.

For info I'm 6'3" with a 34" inside leg.

Cheers

Guy

[Pikey Dave]

I’m guessing they are the Ullman Biscayas that were recently advertised. Ullman offer 3 seat heights, the majority are fitted on the middle one which iirc is 750mm This is from deck to bum. To achieve this, the base is 350mm from deck to seat fixing face. I’m 6’ & the missus is 5’6” & this height suits us both. The foot rests make a big difference too, if you haven’t already got them, I’d get some. These allow you to change your knee angle & are handy to stand on to get a better view over the windscreen. Distance from the helm is a tricky one. In theory, your back should be straight (ish) when you are comfortably sat at the helm with your hands on the wheel. To achieve this with a normal console, you have to place the seat close to the console, this can make it a squeeze getting your legs between the seat & console face. Ullman recommend an undercut console to alleviate this issue, see photo. I can sit with my back against the backrest & my elbows slightly bent, think of a car driving position. Another thing that Ullman recommend is that the throttle & steering wheel are more or less on the same centre line & that the seat is offset between the 2. I.e the seat shouldn’t be on the same centre line as the wheel, this would mean that you have to stretch to reach the throttle. The seat centre line should be slightly offset of the wheel centre line to bring the throttle closer to hand. In practical terms within the confines of a RIB, this means offsetting the wheel & throttle rather than the seat. I only managed to get a small offset due to the size of the console & the windscreen rail, but it does make a difference to driving comfort.
There are some drawings on Ullman's website, These explain it better than I can. http://ullmandynamics.com/informatio...ation-drawings

[Trevor G]

Getting it right is not easy - especially if possible helms are different heights!. As Dave says - to get the distance to the wheel right so you're not stretching whilst sitting back in the seat means the seat base has to be quite far forward. My console is straight with no option for an undercut so got the seat base as far forward as I could live with, then made a boss extension to bring the wheel closer to my body.
I also found that putting the seat at the recommended height made my screen rail exactly in my horizon sight, so I had to made spacers to make the seat about 75mm higher, then use removable shock mitigation flooring (of sorts) to get the right height to the floor for my short legs. This has the advantage that when my son helms, he can take the flooring up as his legs are about a foot longer than mine!.
If possible, make the set up temporary to start with as it's really hard to get it right the first time! (If you want to look at my Ullman setup feel free to pm me.)
The photos show how I used ply spacers to try and get the setup right before making them in nylon. The red seats are how Scorpion set their seats for their chase boat (from the London boat show a couple of years ago when I was trying to get mine right) .

[jwalker]

Try here.... That's not my comment, it's the link's name!


http://www.rib.net/forum/f8/stupid-q...ain-14000.html

[GuyC]

Dave / Trevor

Thank you very much for that.

It was indeed the Ullman Biscaya seats that were for sale recently. They are the XLT 00 seats that are designed to fit on a pedestal. Having a pedestal manufactured shouldn't be too much of an issue and it will allow me to tinker with the height.

I've got a range of heights to deal with from me down to my three year old so footpegs are on the cards. I've no idea how much the Ullman ones are but there are a number of aftermarket - either marine or motorcycle ones that may work.

From your advice I think I've resigned myself to modifying my console to get the wheel and throttle closer to me. It will also allow me to overcome the self inflicted issue of not being able to open the locker doors that are on the aft face of the console. They missed the jockey seats just but they'll definitely foul the Ullmans.

Offsetting the wheel was something I'd seen on the Ullman website. As PD alludes to, it is difficult to achieve within the confines of a RIB. My wheel is on the port side and already overhangs the console slightly so I'm a bit loathe to move it further outboard. In addition my seats are 600mm apart which is the minimum distance that Ullman recommend so moving the seat inboard may cause me an ergonomic issue let alone all the faff with changing the under deck stiffening. I'll have a look when I modify the console but I suspect having the wheel directly in front of me is a compromise I'm going to have to accept.

Once again thanks for the responses.

Cheers

Guy

[jeffstevens763@g]

When I fitted Coastal pro seats my bases were too high I tried steps but found the one position uncomfortable so I had new bases made to suit my leg length much better. If you have a struggle with room between seat and steering wheel consider a flat bottomed steering wheel.

[PaulShark]

Shark now makes the plinth height-configurable (and with fold-down footpegs also) to cater for these situations. We have a lot of seats installed on tour boats that take families (one boat has 36 of our suspension seats). I can post images if anyone is interested