A frame Idea for little rib

[actions]

Now before i start, i'll have to admit, i'm no artist and no computer whizz. So please forgive my drawing attempt.

I've been thinking about adding an a frame to the rib for sometime but after hours of searching can not find anyone that does an a frame for the Pro 420.

I'm looking at getting one manufactured at the local metal works, mainly as i want to add Nav lights. Plus it will be another position for the gopro

You'll note that i've got to come across the tubes due to the steering arm taking up most of the transom area and I cant go any higher as i still want it to go in the garage and the height of the VHF pole is my maximum.

So my questions are -
1. What size of tube should i use to ensure its strong?
2. Should it be bolted through the transom, if so what size bolts? (VHF pole is currently only screwed)
3. Anyone know a rough cost of doing this so I dont get ripped off? Of course i'll fit myself so just after machining and product costs.
4. Will that (very rough) image be stable enough or should i add a second fixing somewhere?

[Glow]

There is one on eBay very similar, item no 290424135018. It's up for £149 plus post though

[martini]

Having the bottom curve out over the tubes before going up is, IMO what causes many a-frames to have too much flex in them. Like the Humber a-frames for example, I think it was Dr Doof's that was well documented on here.

[actions]

Originally Posted by martini

I think it was Dr Doof's that was well documented on here.

Argh yea, i remember that thread now you mention it.

There's not a lot of point in me doing it if its going to flex. I was after it being as solid as possible. I Might have to go back to the drawing board then as lack of transom space around the engine stuffs me a little. A bigger boat it is....... If only

Another option i suppose could be bolting to the transom and coming out from the transom before we hit the steering arm, therefore losing the curve over the tubes. Might make it a bit shopping trolley like though??????.

Ill try another splendid drawing attempt.

[Nick Hearne]

I had one mad up to my drawing last year & very happy with it
Could you not bend it out passed the steering ram or pack it out?

Sorry did not make that clear I mean bring it forward of the transom!

[Ian M]

Have to admit to being a fan of the 'A' frame To my mind you need it to be as solid as possible - it is surprising what they are used for. Mounting lights etc is only the start; ask Nos where he goes for relief. Wouldn't want to feel unsafe when its all hanging out

[actions]

Originally Posted by Nick Hearne

I had one mad up to my drawing last year & very happy with it
Could you not bend it out passed the steering ram or pack it out?

Nick, Thanks very much for that and if i can get something like that i would be very happy. I think i could adapt that very slightly to move out from the arm and therefore avoid the bend over the tubes. Thanks

Whats the size of tube you have used as it looks very strong.

Originally Posted by Ian M

Wouldn't want to feel unsafe when its all hanging out

I couldnt agree more, having made use of the hand rail on the console the A frame would assist greatly.

[actions]

Originally Posted by Glow

There is one on eBay very similar, item no 290424135018. It's up for £149 plus post though

Thanks for the link. Certainly gives an idea on price.

[Nick Hearne]

Originally Posted by actions

Nick, Thanks very much for that and if i can get something like that i would be very happy. I think i could adapt that very slightly to move out from the arm and therefore avoid the bend over the tubes. Thanks

Whats the size of tube you have used as it looks very strong.



I couldnt agree more, having made use of the hand rail on the console the A frame would assist greatly.

It is out of 5cm & yes it is very strong as I wanted & use it for water skiing from & it puts up with pulling me!
+ mine has replaced the original transom supports you get in the Searider so again had to be strong, I recon you could pick the boat up with it! I have now fitted lights to it too.

[john lee]

I made one up out of plastic pipe from wickes diy then took it to the steel fabricators and had it copied in stainless to get the design right,this may help.

[Rokraider]

If you design it carefully, it will be able to utilise the fixing points for the motor and towing eyes, so you wont need to drill more holes through the transom. You should also give thought to how much it will weigh when constructed, it can get heavy quickly.

[jyasaki]

Small RIB? Have you thought about a single upright post? All nav lights can be mounted on it, along with a GPS antenna, VHF aerial, and your GoPro. Saves quite a bit of weight, and simplifies design.

jky

[actions]

Originally Posted by Nick Hearne

It is out of 5cm & yes it is very strong.

Thanks Nick

Originally Posted by john lee

I made one up out of plastic pipe from wickes diy then took it to the steel fabricators.

Thats pretty much what i did for the old boats back rest.

Originally Posted by Rokraider

If you design it carefully, it will be able to utilise the fixing points for the motor and towing eyes, so you wont need to drill more holes through the transom. You should also give thought to how much it will weigh when constructed, it can get heavy quickly.

Hadnt thought about using the existing holes from the towing eye, but that opens up a possible idea of using a more substantial single pole as mentioned by jky (below) utilising the existing towing eye holes. Would also therefore stop any issues with weight at the rear end, something i hadnt given much thought too, but its already a little rear end happy.

Originally Posted by jyasaki

Small RIB? Have you thought about a single upright post? All nav lights can be mounted on it, along with a GPS antenna, VHF aerial, and your GoPro. Saves quite a bit of weight, and simplifies design.

jky

Small Rib = Zodiac Pro 420, i know its bigger than my old valiant and sib prior to that, but smalll when i compare it to most that leave the harbour with me. Normally 5 to 6m ribs.

I already have a single pole for a VHF aerial, maybe if I move / lose the existing pole which is a little flimsy and encorporate a stronger single pole it will provide as you say fixings for the lights and a steady base for the camera. If i also bolt it with the towing eye holes already in place it should also stop the wobble it currently has (maybe) with just simple screws being used.

Oh decisions decisions.

[Rokraider]

I binned the A frame on mine and fabricated a mast instead, along with some lifting/towing rings on the transom. It works a treat for the Safety Boat role it performs. The only thing I would possibly change is the loud hailer, I went with ICOMs recommendation without checking how large it was.

[actions]

I have to say i was set on an A frame, but am certainly coming round to the idea of a stronger and better fixed single pole. I can mount everything i want such as VHF aerial and all round white, plus the camera for skiing.

The other nav lights can probabaly fix to the rail around the console. I appreciate i may be a few cm's out by law with the lights doing this, but its going to be on the very odd occassion on a lovely summers evening that they get used.

The wife prefers a pole idea......Cost wise reasons not pole dancing ones

Do you supply ear defenders for those sitting under the loud hailer

[PeterM]

A couple of my frame on my 4m ....an Outhill one that cost more than I care to think about now !

As said some thought and it could be bolted in the same holes as towing eyes. It does have inserts inside to stop the bolts crushing the tube which mush be maybe 2.5 - 3 inch diameter ( but thin walled) so doesn't support much, but is ideal for use of the onboard 'facilities' as Nos said

[Rokraider]

Originally Posted by actions

I have to say i was set on an A frame, but am certainly coming round to the idea of a stronger and better fixed single pole. I can mount everything i want such as VHF aerial and all round white, plus the camera for skiing.

The other nav lights can probabaly fix to the rail around the console. I appreciate i may be a few cm's out by law with the lights doing this, but its going to be on the very odd occassion on a lovely summers evening that they get used.

The wife prefers a pole idea......Cost wise reasons not pole dancing ones

Do you supply ear defenders for those sitting under the loud hailer

I aim it forward when using it. On the move it is excellent for monitoring radio coms over the wind and engine noise. Downside is when there is a group of us close by and one of the others transmits... Jimi Hendrix would be proud!

[Rokraider]

Originally Posted by PeterM

A couple of my frame on my 4m ....an Outhill one that cost more than I care to think about now !

As said some thought and it could be bolted in the same holes as towing eyes. It does have inserts inside to stop the bolts crushing the tube which mush be maybe 2.5 - 3 inch diameter ( but thin walled) so doesn't support much, but is ideal for use of the onboard 'facilities' as Nos said

If I was making an A frame, I would weld some flat plate onto the tube and mount the frame via the flat plate, rather than bolting through the tube.

[LeeDee]

I purchased the £149 'A' frame on eBay for my Pro 420 and it fitted a dream. It has two fixing points on both uprights and is as solid as a rock. Wouldn't be without the frame particularly on a reasonably small rib when you need to grab hold of something at the rear (so to speak!). I had mine fitted and was told that I wouldn't have got the steel tube for the price I paid for the frame.

[Glow]

Is there any way you can see to make it removable for storage?