When I fit my Mast Ram, with the mast foot approx in the centre of the box, It gives me around a 15 degree mast rake and even with the lever fully forward I cant get the mast more upright .. am I missing something ? 

The obvious solution is to cut the mast ram down in length (it came from another MR so I assumed was the correct length) .. but how much ?

Presumably with the ram connected and fully forward it should actually produce a slight forward rake on the mast, so that when the shrouds pull the mast back it produces bend. I was working on 10 degrees fully forward or does that sound a bit too much.

Can anyone help me out?

Thanks

Steve
MR3226 - nsm1

I have never owned a mast rammed Merlin, but nothing from one merlin has to be the same size as another.

10 degrees forward sounds excessive, I can't see why you would need anything more than dead upright with no bend (i.e. maximum height, maximum sail fullness).

I am no expert.

Just for my mind (!) - I have a "mast ram" from an old Smokers - this fits at the mast gate (keel stepped mast) and pushes the mast back at the deck level. This reduced the low level bend, but I don't see how that connects with the mast heel... 

Are you using a strut and ram?

Colin

I'm not clear if you are talking about a strut running up to support the mast at gooseneck level - probably so and my NSM1 had one - the conventional mast ram operates at deck level to achieve more or less the same effect but is less efficient.  If a strut then I expect you are right and you need to cut the strut tube down a bit.  In practice I can't see why you need the strut to allow the mast to go past the vertical so I would set it there.  Easiest way of establishing this is the dangle method.  Set boat level by using a spirit level on the stem to set it vertical, dangle a weight on the main halyard and there you go.

It would help to know whether we are talking about a hog, case or deck mounted mast.  If hog, then another option is to move the mast foot back a little bit.

There should be be no requirement for the mast to be held by the ram/strut forward beyond vertical.  The object is to ensure that there is no or minimal bend up to the gooseneck, and that any bend is induced above that point.  The amount of bend is therefore a function of the tension and the spreaders, not of the ram/strut.

At least, that's my understanding!

Thanks guys for comments so far .. it is a strut attached to a lever through the deck, and to the mast at gooseneck level.. I note the comment that the mast shouldnt need to go past the vertical forward but shouldnt I be able to bend the mast forward at that point slightly to increase the fullness . or does it work the other way with the vang pulling the top backward creating the same affect?

As you can tell I am rather a novice with mast bending my old leader had no such fancy adjustment. Mind you it didnt go very fast either.  

Steve

Basically the fullness is cut into the sail design. That's why it's important that the sail is cut for the mast & rig you have (e.g. hog stepped masts have different bend characteristics from deck stepped - the sails need to be cut accordingly).
With the mast upright, the sail should have sufficient fullness to give maximum drive (adjust the outhaul if necessary). You will need kicker tension to keep the boom down and to keep the sail from twisting (changed angle of attack to the wind up the mast).
When you pull the kicker, you also bend the mast (backwards). Using the mast ram/strut attempts to keep the bend in the sail part of the mast - reducing the raking of the rig somewhat, and helping to keep the sail full (lowers do a similar job).
As the wind increases, increase the mast bend to lose the fullness until you can sit the boat upright again.

When you use the spinnaker, you'll  pull the top of the mast forward - this can created a forward bend (undesirable) - hence the "puller" on carbon masts.

Have a look at the training pages, the tuning guides etc.

What mast/set up do you have?

Cheers,

Colin

Bending the mast flattens the sail. You only want to flatten the sail when you are depowering or when the wind is very very light (as light wind can't stay attached on big bends - Bethwaite.

As Colin says above, also, fullness is 'cut' into the sail. As I understand (sailmakers please correct me) there are two ways of creating fullness, 
1. Luff curve
2. something else (panel shape?)

The amount you can flatten the sail depends on both factors, you can only pull the 'luff curve' out by bending the mast to match the luff curve => if your sail was only cut with luff curve, logic would say that with a mast bent to match that curve the sail would be 100% flat (usefull on a dead run but nothing else :-)

Thanks Alan

it's been a long time since I thought about this - nice to know I've not forgotten everything!

Sorry didnt have time before battle to read all answers: But in answer to your original question to get mast vertical with exsiting strut pull the mast heel aft! Use spirit level(I am one) on bow & mast to ensure accuracy. 9" of rake good starter. Duck!!!!!!!!!!!!!!!11

"Sorry didnt have time before battle to read all answers ...
Duck!!!!!!!!!!!!!!!"

Francis Drake (not Duck)had time for a game of bowls as well!#

But more seriously, start with the mast raked as suggested - don't pull on excessive kicker, now sail close-hauled and absolutely flat. You should have a little weather helm. Too much and the mast rake is too great - set up the mast with less rake until the boat is almost balanced - you should always (IMHO) have some weather helm, but not so much that you spend your sailing with the tiller over the corner of the transom. That way, when everything goes completely pear shaped (or worse) you can let go everything (uncleat all the sheets) drop in the bottom of the boat. Eventually the boat will come head to wind and stop ...


Colin

mast foot 60 inch back from stem, mast should be able to go forward past vertical - check with albacore sailors. Assume you too want forward rake for downwind in light airs.

As to flat and full sails for light winds - highspeed jet fighter small chord (flat sail), slow speed cessna deep chord (full Sail).

last part was not a statement of what to do! just a thought?

"As to flat and full sails for light winds - highspeed jet fighter small chord (flat sail), slow speed cessna deep chord (full Sail)."

Very true, but the "slow speed Cessna" has an apparent wind of 60 mph+ - in that wind speed I for one don't want a full bellied sail - I want a flatter mainsail - possible reefed as well!

I think the important thing is to have as much fullness at the right place as you can keep upright. When that's too much, start flattening the sail.

Colin

So lets see if i have read all this correctly ..

Step 1 is to move the mast foot aft and see if that gives me a near vertical mast.

Step 2 is to cut down the strut if required to get the mast inside the mast gate.

Step 3 is to set the mast at a rake of approx 9" (whatever that is in degrees) for normal sailing. Less for light winds more for high winds (wont need that for a while then !).. then mark all the settings so I can reproduce the setup every time.

Hopefully the rust can stay on the hacksaw for a little while longer .. thanks for all the advice.

Steve

Oh yes . I almost forgot .. AND DUCK !!!