Liferaft on top of A frame?!

riccardo · 29 November 2011, 18:10

I have been thinking about putting my 14 man liferaft on top of my A frame on a 8.5 meter Humber rib.

It is early days and just a thought at the moment, the idea was freeing up some space for further seating/storage. At the moment the liferaft is just in front of a centre console. The liferaft is just as accessible if mounted on top of the A frame.

Has anyone tried this or seen this done before, some advice on the matter would be great!

Rich

C2 RIBS · 29 November 2011, 18:25

Hi we reviewed this position hanging beneath the top rail of the AFRame on an 8 metre but the overal consensus was the weight issue of a twelve man liferaft some 45kilos up high would change the balance of the RIB. We have seen numerous fittings with liferafts either side of the base of the A FRame just above the tube . Again a wet area and a lot of weight on the stern. I did fit a 6 man to the rear by the wash well area and even this proved to heavy and we had it moved by Biffer on the cradle to the bow area to gain balance back.

I would be looking at the manufacturer to give you weight figures for any loadings. We have found the best place for most of our liferafts to be forward of the consul helm position as all passengers are alongside and to the rear. I guess with a large rear helm the raft might have a good balance if all passengers are ahead of the consul position.

willk · 29 November 2011, 18:42

Dr. Doof put his RADAR dome (5kg?) on his Humber A frame. The frame began to flex badly and it cracked.

Poly · 29 November 2011, 19:26

Google suggests a 14-man liferaft in a canister might weigh 60kg, so even assuming you have the a frame engineered to take that (and the resulting leverage) and the boat balance is fine with it - could you actually deploy it in the sort of seas where a liferaft might be your preferred option? - its sounds hard enough to lift 60 kg at head height never mind when being thrown around in rough seas. The only time I can really imagine stepping off a RIB onto a liferaft being a no brainer is if it is on fire. That's most likely to involve the engine(s) in which case the a-frame really doesn't sound like the ideal spot for it.

riccardo · 29 November 2011, 20:11

Thanks for your response people.

Balancing of the boat were my initial worries. The Aframe will be made to accomodate the liferaft if put there. But the point of when using a raft in a rib from Polwart is a good one!
I'm swaying on somewhere else to put the liferaft!
Thanks

redthunder · 29 November 2011, 21:47

I agree. Most a frames struggle with a radar on it in rough conditions. I think a 14 man liferaft would only last a few big landings.

Andre · 30 November 2011, 10:20

Liferafts should be stored away from the passengers but in an easy accessible place should there ever be a need to deploy them in anger. We found that it is best to have 2 x 8 man packed in flat GRP containers. Here you may have an extra service bill but an 8 man will be much easier to handle then a 14 man especially for a single person. We fitted such arrangement on SeaSafari 1 and even with this extra weight on the stern it made no difference to the performance of the rib.
Looking at the attached photo you can see that even with 14 persons on board and the two 8 man liferafts the tubes still do not touch the surface of the water.

The photo of the yellow rib (a Parker 1000 Baltic) shows a similar arrangement

Courageous · 30 November 2011, 13:51

You get a degree of redundancy with 2 8 man rafts as well of course.

chewy · 05 December 2011, 19:53

Quote:

Originally Posted by willk

Dr. Doof put his RADAR dome (5kg?) on his Humber A frame. The frame began to flex badly and it cracked.

I thought them Humber A frames vibrated more than an Ann Summers party full of middle aged women anyway..... and then self destruct.

Swifty · 05 December 2011, 21:06

Quote:

Originally Posted by chewy

vibrated more than an Ann Summers party full of middle aged women anyway..... and then self destruct.

Is that not called a crisis?

hobbit555 · 06 December 2011, 04:52

If you are building the a frame to suit, and setting aside the top weight issues, the next issue is the sheer size and weight of the raft canister. There fore could you design a quick release system that on pulling "a pin" release the raft over the stern and straight into the water. All this from maybe just above the outboards and under the a frame?

chewy · 06 December 2011, 06:39

Quote:

Originally Posted by Swifty

Is that not called a crisis?

If your A frame turns into a quivering wreck and falls to the floor then yes it would be, the middle aged women at a Ann Summers party may be a different matter....