Just a thought ... anyone ADDED a Transom Arch ?

Chiara’s slave said:
With carbon, it might be strong enough to pick the boat up with, but you wouldn’t want the mast to hit it, ie zero mistakes on lowering.
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We use a lot of CF rod / tube in modelling nowadays to strengthen lightweight construction. One of the first things you find out is that CF splinters ...... and those splinters are bad news !!
 
Refueler said:
I am aiming at the smaller sailboat ... 20 - 28ft ... where its not often you see a transom arch.
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Interested if anyones designed their own or had one fitted ??
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Here is mine on my 26 ft Trailer Yacht. Single ss tube of 1 inch. I made a bender and bent it up and welded it myself.
It serves multiple functions:
* I have a removable V roller that the mast drops into when lowered for transport. It wing nuts onto the bracket you can see top middle. This was the primary purpose to avoid the horrible removable vertical leg support that i used to have. (I have invested a lot of effort into minimising time and faff for rigging and unrigging, and this helps.)
* When cruising I have a couple of small solar panels that attach to it using pipe clamps.
* I have an awning that attaches to it for shade at anchor.

I wanted to minimise windage and weight for obvious reasons, so decided to try a single tube and see if it was strong enough and rigid enough in practice. Had it not been strong enough i was prepared to rebuild it with a two tubes, but several years later i can report that this has suited my needs very well.
 
Refueler said:
We use a lot of CF rod / tube in modelling nowadays to strengthen lightweight construction. One of the first things you find out is that CF splinters ...... and those splinters are bad news !!
Click to expand...
I was fairly sure you’d know that. Hence stainless, wood, alloy and GRP being the favoured materials, though I’d be careful about the alloy too. Your mast being heavy (I could trot round the boat yard with mine under my arm, literally) you clearly know what this arch is going to need in the way of strength. If your mast does more than a gentle bump it’s going to need to be made of Kryptonite.
 
Not wanting to pay circa £6k for a steel arch a jeaneau42ds which crossed the altlantic built a frame for his solar panels etc using the standard tubing used for spray hoods etc. I guess with enough bracing struts it could be used to hold a mast .I guess it depends on weight of mast and how many bars you combine of ss tube and how much strut support you have. This I suspect is the 2 tube option mentioned JtK above.
 
Just how heavy a mast do you want to hold?

My single 1 inch SS tube supports my 110 kg doing chin ups and that is with the mast lowered and also resting on it for transport!
My mast is 30 ft long. I have done hundreds of road kilometers with the mast supported on the arch.
Being a mechanical engineer, I wasn't just guessing when i made this.
I think the most likely mode of failure is fatigue cracks at the top of the weld where the pushpit /braces are welded on, so I keep an eye open for that, but no problems so far.
 
John the kiwi said:
Just how heavy a mast do you want to hold?

My single 1 inch SS tube supports my 110 kg doing chin ups and that is with the mast lowered and also resting on it for transport!
My mast is 30 ft long. I have done hundreds of road kilometers with the mast supported on the arch.
Being a mechanical engineer, I wasn't just guessing when i made this.
I think the most likely mode of failure is fatigue cracks at the top of the weld where the pushpit /braces are welded on, so I keep an eye open for that, but no problems so far.
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I'm confident that similar in a twin parallel form should be more than enough. I would hope to match the tubing diameter of my Pushpit .....
 
John the kiwi said:
Here is mine on my 26 ft Trailer Yacht. Single ss tube of 1 inch. I made a bender and bent it up and welded it myself.
It serves multiple functions:
* I have a removable V roller that the mast drops into when lowered for transport. It wing nuts onto the bracket you can see top middle. This was the primary purpose to avoid the horrible removable vertical leg support that i used to have. (I have invested a lot of effort into minimising time and faff for rigging and unrigging, and this helps.)
* When cruising I have a couple of small solar panels that attach to it using pipe clamps.
* I have an awning that attaches to it for shade at anchor.

I wanted to minimise windage and weight for obvious reasons, so decided to try a single tube and see if it was strong enough and rigid enough in practice. Had it not been strong enough i was prepared to rebuild it with a two tubes, but several years later i can report that this has suited my needs very well.
Click to expand...

Nice one .... I had not considered single tube design - as usually you see it in two parallel form ......

Food for thought.
 
Little thought, if setting it up for mast support, I would be tempted to use a removable strut to brace the arch directly down to the stern deck, rather than more diagonal braces that might get in the light most of the time.
 
My stainless tube targa bar is on my 28 foot trailer sailer and is attached to my push-pit by heavy duty bimini fittings, it is made from a pair of stainless tubes in parallel and has been designed to carry the mast when lowered on a protruding roller with catch sides, it has a largish solar panel attached that can tilt in the bow to stern plane, has my vhf ariel mounted high on it ( which folds down and lays across the top for trailering, is also the rear support for my bimini and has my dingy outboard mount on it.
Further to this by detaching the rearmost legs it can swivel right down with both front and rear legs secured by large thumb screws and can then lay parallel to the deck just behind my steering wheel substantially lowering my air draft if really required. 34FEB39E-2592-493D-89B1-D1CAD5A099B0.jpeg71A86BDA-2D8F-45DB-BBB9-A844C13D75C0.jpeg
 
All above posts greatly appreciated and read .... continuing and revisiting thoughts :

Superanne has a good pushpit and I have often wondered about adding an arch above it. To a) take an AIS antenna and remove the splitter from masthead VHF antenna, b) provide base for any solar I might add, c) to provide a mast 'crutch' when lowered.

Pal of mine bought a solar panel ... I did warn him it was a little big and better to buy a couple of smaller ... but it came and now he has a problem of where to mount it. He went to local Majas Damas (our version of B&Q) .... bought chromed pipe and fittings - created an arch for the large panel. I looked at it and my wish for an arch surfaced again.

Yes its chromed pipe and fittings - but luckily Baltic is brackish ... not full on 1025 SW .... so with care and bit of polish now and again may last a few seasons. But idea is to create in this as cost is dramatically less than 316 and no welding needed. If its truly successful - then I can get my mate to fashion in Dural or 316 ...

Most stainless prefab arches I see - have an angled leg each side going forward while having a vertical behind it. They also are designed to bolt to the stern area and not clamp to the pushpit.

The fittings at local shop allow me to have a dual vertical and transverse but without angled leg forward ... same fittings another showed earlier ..

I realise that c) will be limited and extra support will be needed to the transverse bars ... I would likely still use my wood X frame allied to the arch. ...

The boom stops well short of the area - so not a problem.

Given the usual height of pushpit referenced to person standing in cockpit of most 1970's boats ... how high would you make the arch above the pushpit ? The pipe comes in 1m, 2m and 3m lengths.

I am thinking somewhere between 0.75 and 0.9m clamped to the pushpit ... so it doesn't look like a marquee frame !!!
 
My whole rear targa bar and Bimini structure has developed to now be capable of carrying up to 720w of solar panels in 4 180w rigid thin frame panels. All are attached by thumbscrew tightened clamps and can easily be removed when I am not long range cruising or easily dropped to 1 or 2 panels for battery maintenance as distinct from bulk solar power production.
3 of the panels clamp onto my 1 inch stainless tube Bimini frame creating a hard roof over the canvas Bimini. One hangs off the rear of my targa bar and is tilt able in the fore aft plane.
The targa bar and Bimini frame are all bolted to the sturdy stern pushpit with stainless adjustable fittings allowing the whole structure to both tilt and completely fold forward by just loosening or undoing thumbscrews.
The structure also tilts and carry’s my mast above it all on a targa bar mounted roller for trailering
I have further stabilised the whole structure now replacing the Bimini forward straps with stainless tubing again able to accomodate tilting whilst providing more solid trailering support.
With the exception of the custom targa bar that came with my secondhand yacht all the rest has just been cobbled together from propriety Bimini fittings, an off the shelf Bimini and a couple of lengths of stainless tube combined with a number of clever plastic thumbscrew solar panel mounting clamps from a company in America. IMG_0356.jpegIMG_0367.jpeg
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Obviously my package is for long term liveaboard exploration/adventuring not racing. 🙂
It has to date withstood several week long cruises including an over 30 nautical mile crossing in 35 knot winds with a short very steep chop of a huge ocean adjoining shallow freshwater lake and several hundred miles of towing.
It has a several thousand mile towing test about to occur as we drag the yacht from southern to northern Australia.
My English friend who accompanied us on the recent local cruise joked that crossing Lake Alexandrina here in Australia was further than his English Channel crossings!
 
Refueler said:
Another thought of course .... with boom and mainsheets of to the side - I could actually create a 'bimini' from the arch to the sprayhood when moored.
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I covered that with a second cheap Bimini that neatly tucks under my main one and folds out overlapping the over dodger and just under the rear Bimini providing total overhead cockpit cover at anchor for the tropics. It has a bag storage cover and the main sheet has a second forward attachment point on the boom neatly passing the main sheet from this forward boom attachment point down to the binnacle attachment point angled through the small gap with just enough movement clearance. IMG_6355.jpeg
 
Hi Grith ...

Tks for all that ... gives ideas and helps me confirm that my idea may not be so daft.

I am not planning so much construction though ... the main idea is to carry a couple of small solar panels to maintain batterys ... and revert back to my transom mount AIS antenna.
The mast bit - I don't expect to be able to carry weight of mast on it without additional vertical support ... my mast when lowered has significant rear overhang making it a real load there ...

Q1EdCfEl.jpg


That is the position mast will have to transit the bridges .... (you can see that the metal pipes used to provide higher point for tackle has bent already !! Needless to say A frame proved much better .. ). Its an old photo ...
 
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