Magic 25 Mast Ram

[JulianB]

6Pac was a T8, nice boat, previous owner optimised it, for SMS and we sort of accidentally won the Nats in 2020, but it certainly went fast.

RAM was great until it wasn't, having to sail the Islands race with no hydraulics was not fun, but we still won.

Had to cut into the deck to get the ram out, Fleet-Hydrol is 2 km away, and they fixed it, but it was about $2K to have serviced, sold the boat shortly thereafter so can't comment on whether is still operational or not, the boat is in Tasmania I think.

Always thought a screw jack would have been simpler.

 

[Sailabout]

6Pac was a T8, nice boat, previous owner optimised it, for SMS and we sort of accidentally won the Nats in 2020, but it certainly went fast.

RAM was great until it wasn't, having to sail the Islands race with no hydraulics was not fun, but we still won.

Had to cut into the deck to get the ram out, Fleet-Hydrol is 2 km away, and they fixed it, but it was about $2K to have serviced, sold the boat shortly thereafter so can't comment on whether is still operational or not, the boat is in Tasmania I think.

Always thought a screw jack would have been simpler.

Crikey I think they sold me a new one a few years back for $1200 plus parts to fix the old one.

 

[DE1]

agree JB, i think it cost us $1500 for a brand new ram back in the day when we firts fitted out the T8 boats. Any good ideas to imulate that mast jack idea as you are engenere and boat designer and sailor !!!

 

[neuronz]

We are using a small screw jack with a fine thread to lock down our keel with a wedge. Works very well and I can imagine one could use a similar system under the mast. Big advantage of hydraulics is IMO that you can easily add a meter to read pressure which makes it easier to record and replicate settings and also helps to prevent overloading. The fine thread just keeps on going with very little difference in force.

 

[Dead air]

Hooking a pressure gauge to a ram on an M25 wouldn't be easy , would require a bit of custom work, and provide another failure point. We just measure the ram extension, can easily be measured to the mm and far more repeatable.

 

[Sailabout]

Hooking a pressure gauge to a ram on an M25 wouldn't be easy , would require a bit of custom work, and provide another failure point. We just measure the ram extension, can easily be measured to the mm and far more repeatable.

there is a port for it and FH sell the guage ready to go into it.

 

[JulianB]

On our T8 we had a pressure gauge on the ram, and at the end of the day, it's about rig tension, so we referred to the gauge often, during a race and certainly between races. The one on our boat allowed the mast to rotate. Not sure that's clever!

I guess the big failing from my POV is that as you pump the mast up, which you tend to do as it gets fresher, your not going to "stretch" the forestay so you are reducing rake, as you do it, which is not what you want. I extended my forestay by 15mm (more rake) and the boat took off. So a well set up set of turnbuckles on the shrouds, I think, is a smarter way to go.

Re a screw jack, 1stly I am not a NA or a Engineer, I loosely call myself a Industrial Designer, and I had an extraordinary up-bringing which immersed me in fluid dynamics.

The M thread system tend to be prone to failure under constant adjustment, so you probably need to use UNF or more likely a square thread type. I look at the threads on car jacks and they do it so simply.
But this "jack" re T8/M25 would need to be rated to 5-8 tonne at a guess max download. Adjusting between races it's only going to be 1-2 tonne load.
Looking at the Fleet-Hydro ram, pretty obviously a 40mm dia pin is strong enough, so if you started with a 50mm pin, cut some threads in, 10-15mm high nut in a cage on some igus thrust bearings, be pretty simple thing to get made and nice carbon spanner, pretty idiot proof!

I could spend some time and draw it up, if you really want me to, get it made out of SS and Ti.
Just sit it on the deck, I would have to go look at a M25 to work out the base plate but it could be very simple and just slot in.