[ Resources ][ Shipping Weights ][ Tech Tips ][ Boat Show Schedule ][ Literature ]

Tech Tip

YACHT RODS/BOOM VANGS

Forespar® makes three sizes of spring loaded boom vangs for boats starting around 30 feet and up to about 55 feet. These units are rugged, a good value, and have many thousands of ocean miles under hundreds of boats all over the world. We do not offer the most purchase or have any “locks” or fancy stuff. These are work horses designed to do the job on a general cruising boat or club racer. They will work very effectively if installed correctly and not abused. Some basic points to remember:

• The boom must be fixed, non-rotating and non-sliding on the mast. Roller booms or sliding goosenecks will not work with any rigid vang. The boom fitting or the upper vang head will fail if the boom can “roll”.
• The minimum angle from the boom should not be less than 30 deg. and no more than 45 deg. Lesser or greater angles increase the compressive load beyond what a spring- loaded vang can handle. Hydraulics is the only answer beyond these angles.
• Yacht Rods do not “lift” the boom. Only hydraulics can do that. These do take the place of a topping lift. They will hold the boom up while dropping sails or reefing. Properly set up, they will keep the boom level when the main is furled.
• Do not attempt using a standard spring-loaded vang with an in-boom furling system. These furling units are far heavier than a standard boom and these vangs are not suited for this type of boom.
• The “stroke” is the total maximum compressed travel of the spring/piston. Once the spring bottoms out, the unit will fail if further compressive force is applied. We offer a minimum of 7” on the medium Yacht Rod and 11-1/2” on the large and extra large units. This should be plenty of travel. If, on an average 40’ cruiser, they need to “vang” the main down more than 7”, the sail is cut wrong!

We make mast and boom brackets to fit our ends. We require that they be used. They must handle a tremendous compression force and still articulate in line with the boom. They are every bit as critical as the booms gooseneck. The boom fitting must fit snugly to the vang end and “spread” the load on the boom. This fitting sees compression and tension. The boom attachment must be capable of handling these forces without kinking the boom. A lot of race boats loose their booms due to failure at the vang fitting.

Rigid vangs can rattle, squeak, or make other noises under sail. They all do to some degree. We cannot guarantee ours will be completely quite, but from the hundreds of installations in the field, we are not hearing of any major noise problems. Do not oil these! The oil will simply flow out and end up on deck. Keep them clean by flushing with fresh water periodically. No other maintenance should be needed other than watching for worn line, dents or bends. Do not use a unit that has been damaged or over-compressed.

Common care should keep the Yacht Rod working for many years and nautical miles.

Sizing yacht rod boom vangs

Choosing the correct size rigid vang requires the following information:

1. Distance from mast fitting to boom fitting at the proper angle from the boom per the previous spec sheet. This will tell you what length requirements you have for using the “pin to pin” dimensions on the Yacht Rod size chart. (Found in the 2001 Forespar® catalog, page 20) Note that it is possible to have a low boom on a large boat that makes this dimension inaccurate. Be sure to check angle and length.
2. Be sure you do not have any obstructions (hatches, vents, cabin tops) in the way of the Yacht Rod’s arc of movement. Remember that it will need clearance through 180 degrees of movement from side to side.
3. Check above dimensions against the catalog’s boat size recommendations. If you are close to the maximum, you may need to go up a size to support your boom and sails weight at rest. (Furled) Do not undersize!
4. Install mast fitting as low as possible on aft centerline of mast.
5. Install boom fitting to get proper angle per previous specs sheet. You may want to clamp the boom fitting in place first, before you drill any holes; to be sure it is in the correct position. This way, you can ease the weight of the boom and furled main sail onto the unit to find out how much the spring will be compressed at rest.
6. Adjust the cross pin as needed being sure the spring is between the pin and the inner piston tube. Do not set the pin through the spring!
7. Whenever the sail is furled, it is best to set the main halyard to the outboard end of the boom to support the booms weight. In this way, the Yacht Rod spring will not take a “set” from being compressed the whole time the boat is not in use.

Basic sizing:

34-40 feet- Yacht Rod Medium #352000 or package #352050

41-45 feet- Yacht Rod Large #352100 or package #352160

46-55 feet- Yacht Rod Extra-Large #352101 or package #352165

Packages include the mast and boom brackets and tackle.