What to Do With Mast Rams

The 505 rig is more adjustable and tunable than most other racing dinghies, particularly the simpler "lower tech" boats. When you first get into a 505, you may wonder what to do with the mast ram - here are some ideas. These are from the e-mail distribution list. Thanks to Warren for first raising the question.
Warren asks.... So what's this mast ram thing anyway???

I'm in the process of figuring out how to sail my newly acquired 505 to its limits and was wondering about its more subtle adjustments.

Mine is a Parker 7994 rigged with vang sheeting, adjustable shrouds and headstay. It also has a mast ram which I as of yet have not figured out. Can any one summarize when and where and how to use it properly? What weather conditions? What points of sail. How to incorporate it with tension of the shrouds, headstay, sheets, and vang. And what effect it has on mast and sail shape?


A response from Will Hartje....

Mast rams work will work differently depending how

a) your mast is rigged and
b) the bend characteristics of the bare pole.

Releasing, or easing off the ram will generally cause two things to happen; the mainsail will flatten below the hounds as the mast bends, and the leach will open all the way up.

Both of these phenomena will lose you power out of the rig, which you may want to do in a big breeze. Sometimes it is useful to have the mast flex a little in the gusts to ease the leach and then recover.

It depends on how bendy your mast is, how full your main is, how heavy your crewman is and where the stays and trapezes are attached to actually figure out the behavior, but for a rule of thumb start by sailing upwind with the mast rammed up solid and the cunningham tight. If you are overpowered try easing it a little to see the effect. Once you get the leach too open you will lose speed rapidly and the boat will feel underpowered.

Off wind we usually released the ram, especially in a blow.

Hope this helps

Will Hartje Whartje@aol.com


And another from Ali Meller.....

Here is what I do.

I set up the mast (and the rest of the rig) to go upwind. When going downwind, I simply hoist spinnaker, raise board, and ease vang. For upwind sail trim.

The mast is never straight fore and aft; you always have some amount of fore and aft bend. The mast ram can reduce bend (pull ram down), or increase it (pull ram up).

For normal light to medium conditions, set your shrouds and forestay so that you have about 500 pounds on the shrouds (I use a Loos tension meter, or 500 pounds is tight, but not very tight), pull the ram down to get the mast straight, and then hoist a tape measure using the main halyard. I measure to where the transom meets the hull. Standard measurement is 25' 8". when i actually put the boat in the water, i" ease the ram to get some bend into the mast. In very light, I will pull the ram up to get more bend. More bend flattens the main. In very light air (crew sitting inside the boat) upwind, I will have lots of induced bend. As the breeze comes up, and the crew moves to sitting on the tank with the skipper, you can pull the ram down, to straighten the mast a little, and get a more powerful mainsail shape. Though the mast never goes to straight, it gets closest when you have the crew on the trapeze, and you are fully powered up, but you are not overpowered. If it is windier than that, I rake first (ease forestay, tighten shrouds) to 25' 7"," I also pull the ram DOWN as I want to keep the same bend as I rake aft. As the breeze builds and I am overpowered again, I continue to rake aft, this time leaving the ram where it is. In very windy conditions, I may be raked to 25' 2" (boom is quite low at the back), and have considerable" mast bend.

When flying the spinnaker in any breeze, make sure the mast ram up control line is cleated. That will prevent the spinnaker pole pushing back on the mast, straightening or even inverting it.

Any time you adjust ram (up or down), you should check your vang adjustment. If you ram down (straightening the mast), you probably need to ease a little vang, and vice versa. You should have a telltale streaming off the leech of the main, near where the top batten goes. Try to keep that streaming some of the time (stalling up to 1/2 the time is OK in flat water). Regards, Ali