New A Frame Time? - Page 2

Zippy · 26 October 2004, 08:06

Quote:

Originally Posted by Hightower

Carisbrook, great place!!

Zippy, if you want a pattern and in ,my area come on over to my place and measure my A frame on the Deepsea. Its only a single and it only bolts onto the transom, very tough and I'd be happy to swing around on it in a F8. Has all my nav lights, gps and vhf hanging on it! Could show you the dash and screen I've made for the consol at the same time.

Andy

Thanks Andy,

Will have a measure of mine this afternon when have picked it up!

Cant really do much till then but will drop you a pm to organise a time and place.

Unfortunaty having taken yesterday and today off work i can just guess what mess im going to find on my desk tomorrow. may have to be the weekend now as its dark in the evenings by the time i get away from the office.

Howard.

DGR · 26 October 2004, 08:40

I've got a big double A-frame on the back of my 7.8 - it is bolted through the transom, and the front legs are bolted through the hull. The bolt heads are recessed into the hull surface, but you can still see them!! It seems quite secure......

D...

George8910 · 26 October 2004, 11:46

How sturdy does an A-frame need to be to tow a waterskier? I have seen simple ski poles advertised on boating supply websites but it's not clear if these would be suitable for a rib...

George

Bilge Rat · 26 October 2004, 11:51

Quote:

Originally Posted by ADS

I think that could be Bilge Rats boat.

It is and Rogues now wrong (sorry Rogue) since this pic was taken i've changed my engine to a 60HP Yam 4 stroke and it only just fits under the A frame with the engine tilted up, it was made to measure by a local guy to me that does stainless work, the remit was it fitted under a standard 6' garage door and it does, what i didn't take into account was one day i'd want to change the engine and bigger 4 stroke would have problems lifting under the frame, ho hum its not that bigger deal really and something i can live with.

Its has feet on the inside tubes that each have four big screws going into the deck and the transom tube is fixed by 3 bolts each side going through the transom, three plates welded between the tubes each side an a big one along the top where the lights, ariels and antenna are mounted, all wiring goes down through the inside tube.

CND · 26 October 2004, 11:54

Have you thought about putting hinges on the bottom of it and allowing it to fold down into the boat?, with two clasps/clamps to keep it upright against the transom when afloat? this configuration allows you to reduce wind resistance while towing and get the thing in your garage. I have seen two or three boats now like this and am more impressed every time!

Bilge Rat · 26 October 2004, 12:06

CND...this sounds like a good idea, however i wanted a double A frame and funds at the time did not allow these sorts of additional things, mine was the first A frame he'd made, i changed the design halfway through which didn't help either, i know believe my decision to fit a double to be the correct one.

In essence the A frame is for mounting lights and instrumentation to gain height and its not recomended to tow from it unless its been specifically designed or re enforced to do so, most ski poles go through the deck and are fixed inside the hull, i've saw a single stainless steel frame snap like twigs towing a flooded canoe !!!

Supose it all depends what you want and remember the more weight you add at the transom the slower your'll go !

Zippy · 26 October 2004, 18:21

Well its arrived and!!

Was out looking at it earlier before it got dark and woundering about fixing.

I want to fix the front down tube to the deck. my question.... sould i be looking to epoxy and glass a block of wood onto the deck to screw into? i dont have under deck tanks so thats not a worry.

Then the back down tube can be bolted through the transom.?

Any thoughts??

Thanks
Howard

Hightower · 26 October 2004, 23:49

You'll have to find a fixture that goes in though the deck like a toggle bolt or something. If the layup is like mine you can't simply remove the rear deck gland and simply stretch under to screw a nut on the end of a bolt as the transom supports that go below deck level, also run lenghways down the inside of the hull toward the bow to support the deck and prevent you from placing the A frame in the Ideal position. The only other way to securley attatch a double A frame could be to drill through the hull right where the tubes meet the deck and putting dome head screws though, but I don't like the Idea of drilling though the hull below the water line.

I'm sure someone else could come up with a more suitable fixture Idea though.

What's wrone with a single?

swginn · 27 October 2004, 07:39

My, forward legs of my double A-frame are bolted through the hull, and have 2 reinforcing stainless plates on the waterside of the hull. It makes the A-frame very solid and has given me now trouble, with water ingress or anything else for that matter. Ribcraft do this also, and they have had no problems up to now with it either as far as I know.

I'll post some pictures later when I get home of the stainless reinforcing plate. I would imagine it would strengthen the join between the transom and hull as it is bolted to both.

Zippy · 27 October 2004, 19:53

Humm...

Maybe I should take the easy option and have a really substantial single frame.

Easier and cheaper to design, produce and fit but more hassle fitting things too..

ollyit · 27 October 2004, 20:20

thats waht im going to do I think zippy

Nasher · 27 October 2004, 20:27

Olly Hi

Be careful, as a double frame has more mounting points and can be fixed a lot more securely because its fixed to the transom and floor.

Nasher.

Red Fox · 27 October 2004, 23:00

Today seen a single A frame fitted to new Zodiac Pro 12. It had two bolts on either side about 30 cm apart, fitting through transom. It was about 70-80mm in diameter and seemed very solid.

Red Fox · 27 October 2004, 23:32

better pic

Hightower · 28 October 2004, 00:50

Absolutly no problems with my single A frame. Its really solid!! At the end of the day, what's your A frame going to do? Pull a Skier or another boat, to support the transom to mount a self righting airbag or just to hang nav lights, burgees and antennas off of?

If the latter there's no prob with a single, but if you don't think singles are sexy is a double worth the extra money and more timely installation.

Seems easy to me. Go and have the single made, fit it to your RIB and see what it's like. If you don't like it or your circumstances change, get it upgraded to a double. It'll cost the same in the end but might just save you some hard earned greenbacks if you like the "first attempt"!

tcwozere · 28 October 2004, 11:03

This is my single "A" frame, built by Carisbrooke. It worked out at around £130. It's made with 40mm s/s with mounting brackets for nav lights. They put some eyelets and cleats on for flags etc. It also came with two slab's of metal to bolt to on the inner side of the transom, cept the original "U" bolts are in the way.. It was going to be placed inside the transom, cept the steering arm is in the way..

Bilge Rat · 28 October 2004, 11:18

Quote:

Originally Posted by tcwozere

This is my single "A" frame, built by Carisbrooke. It worked out at around £130. It's made with 40mm s/s with mounting brackets for nav lights. They put some eyelets and cleats on for flags etc. It also came with two slab's of metal to bolt to on the inner side of the transom, cept the original "U" bolts are in the way.. It was going to be placed inside the transom, cept the steering arm is in the way..

So not very well thought out or planned then !!

Bilge Rat · 28 October 2004, 11:28

A single tubed A frame will no matter how strong the fixing points are fold over at the point where the tube meets the top edge of the transom if enough pressure is applied from behind, so its irrelevent how many bolts or fixing points go through the transom, the weak spot will always be the spot where the tube clears the transom !! this is fact, i've seen single tubed A frames bend and snap with only a small amount of loading.

This is less likely to happen to a double as there will have to be additional fixing points inside the boat, this means the structure is more stable and less likely to be bend at the same point as a single ! the obvious down side of a double is the space it will take up and the extra weight (depending on tube size) at the transom, on a small boat weight and space are at a premium.

You need to decide what you want the A frame for, if you want to tow a wake board then your best to go for a big double, fix the anchor points through the deck and transom and run cables to the bow to take the loading, if however you just want to mount an ariel and some lights then a single will of course do the job adequately enough.

tcwozere · 28 October 2004, 11:28

Quote:

Originally Posted by Bilge Rat

So not very well thought out or planned then !!

nah..

way more fun like this..

tcwozere · 28 October 2004, 11:31

I agree with the strength comment, the top of the transom has a lip towards the back, so when I bolted the frame on, it had have spacers. but, as the frame is only going to be used for lights and flags, strength isn't a worry. It's not gone onto a rib that will be used in extreme conditions..