Belt and braces, and a bit more for luck....

[zoidberg]

I completed mounting this bright, shiny addition late last night - which proved difficult for me to mount, due to complexities of access for 'beefing-up underneath'.

Please excuse the blue MDPE pipes which help support the tarpaulin.... and the 'grubby bits'.

It 'borrows' from the Selden kit in concept, and uses the same T6061 alloy, but has an 89mm OD ( instead of recommended 75mm ) and twice the wall thickness. That makes it a bit more than twice the weight, but less than one-tenth the cost. I also saved the cost of reinforcement and installation.

The paint job isn't quite as smart, but then the end-caps are real teak and not rotomoulded plastic.

I had thought to sleeve the thing in a 'wrap' of plastic carbon-fibre weave, but I sensed my sailing club mates would just 'take the emissions'....

 

[Bodach na mara]

Bow-chaser canon? Torpedo tube? Rocket launcher?

 

[Mister E]

Raming device?

 

[Neeves]

I doubt the alloy would b commonly used for armaments and battering rams were usually attached to fairly heavy duty vessels.

An alternative use might be for an asymmetric lightweight headsail - for which it seems more than adequate. I would like detail of the ring at the forward end and the backing for the pin (if used as I suggest might be more appropriate). The pin takes a lot of tension hence the heavy duty prodder and the ring looks that little bit whimpy.

Jonathan

 

[rogerthebodger]

I made a bow sprit from stainless steel schedule 40 tube that would pass through the average GRP hull easy.

I made mine removable, so the I/A length is lowered to reduce mooring cost

 

[zoidberg]

An alternative use might be for an asymmetric lightweight headsail - for which it seems more than adequate.

Now that's a good idea....!

I would like detail of the ring at the forward end and the backing for the pin (if used as I suggest might be more appropriate). The pin takes a lot of tension hence the heavy duty prodder and the ring looks that little bit whimpy

At present, the M12 ringbolt - rated at 2500kg - is secured with a Nyloc nut. I'll add what the 'Murricains call a fender washer when I find one.
I'll also sort out something cheap and cheerful at t'other end to prevent 'to-ing and fro-ing'....

 

[Neeves]

Images can be so deceptive it looks --- wimpy - but if 12mm fine. But my query was maybe two fold, ring bolt shaft, but also the strength of the prodder specifically where the ring bolt is located - that's where all the tension is focused and the loads will vary as the yacht is hit with gusts or you run over swells. I'd have had a backing plate curved to fit the pipe underneath and similar on top. The loading surface, what ever it is, is then curved and most nuts are flat . You need some sort of curved spacer, lets call it a washer - curved to match where it mates but flat to accept the nut. If that's a 'fender' washer - we learn something every day.

I might also belt and braces - if there is room and use a nylon nut on the ringbolt shaft where it enters the prodder and exits - inside the shaft (with more washers). You don't want that ring bolt moving. This might demand your soliciting the help of one with small hands.

You will find as you accelerate and run down swells the tension will all drop off and the sail may luff, opposite as you go up the swells.

I confess my memory is a bit poor and forget other work you have done on the rigging - but the tensions imposed by a decent asymmetric in big seas are not to be ignored and I hope you have a decent back stay and, if appropriate, running back stays.

As a work in progress and noting your obvious parsimony engendered by an education that of which Knox would approve (he of strong Protestant ideas) it looks to be developing well.

Jonathan