Rodkickers and Boomstruts are a practical, user-friendly concept for supporting the weight of the mainsail boom on a sailing yacht, preventing it from dropping to the deck.
Barton Boomstruts and Selden Rodkickers (with a Gas Spring fitted) effectively obviate the need for a topping lift.
The advantages of a rigid boom support system:
- The option to dispense with a topping lift
- The reduction of windage and weight aloft
- The ability to maintain a fixed angle between mast and boom
- Protection of the deck and the crew from an accidental boom crash
The knock-on effects can be extremely beneficial:
- Secure and more efficient mainsail reefing
- Simplified mainsail drop into a lazyjack system
- Useful control of the boom angle for in-mast and in-boom mainsail roller reefing
- Improved mainsail setting in light airs
N.B. Depending on the specification of the line, an existing topping lift may serve as a spare halyard.
Jimmy Green offer two different design concepts in rigid boom vangs, also referred to as boom support systems.
They are both from top manufacturing brands, one from Barton and one from Selden.
The Barton Boomstrut Support System is a simple, but clever, patented design based on a flexing spring concept.
There are essentially only three major parts - a pair of coated fibreglass rods, secured together at each end with a set of removable clamps, a mast end bracket and a boom end bracket.
Fitting the brackets is relatively simple regardless of the spar manufacturer, especially the mast end which slots into the luff groove.
The clamps and end fitting brackets are manufactured from Spectro Grey Anodized Aluminium and 316 marine grade stainless steel.
The Barton Boomstrut should be fitted inside the triangle created by the existing kicking strap, although some adjustment may be needed on some rigs.
The vang can remain unchanged, but is still a fundamental necessity. However, the topping lift may be consigned to the role of a spare line.
Select the correct Boomstrut size by Yacht Length Overall:| Barton | Boat Length | Pin to pin length | Max rod reduction | Max initial adjustment | Force |
|---|
| 44001 | Dinghy | 762mm | 125mm | 250mm | 35kg |
| 44010 | 6m | 960mm | 150mm | 300mm | 90kg |
| 44020 | 6-7.5m | 1070mm | 150mm | 300mm | 140kg |
| 44030 | 7.5-9m | 1180mm | 150mm | 300mm | 185kg |
| 44035 | 9-10.5m | 1320mm | 150mm | 400mm | 230kg |
| 44040 | 10.5-12m | 1450mm | 150mm | 400mm | 270kg |
Pin to pin length = actual length of the boomstrut
Max rod reduction = The maximum amount the boomstrut rods can be shortened in order to fit inside the vang area.
Max initial adjustment = The maximum amount of available pin-to-pin travel when flexed.
Force = The vertical downward pressure that the boomstrut will support at the point of the boom fitting attachment.
The Selden Rodkicker is a telescopic anodised aluminium section (rod or pole) with an integral 2:1 wire purchase system, an internal dampening buffer, an optional lifting ram (gas spring) and end brackets for attaching to the boom and mast sections.
The rodkicker is designed so that one aluminium extrusion slides inside the other with the help of easy-glide nylon (plastic) end plugs and bushes.
These plugs and bushes are also designed to help dampen any effect of the rod sections accidentally bottoming out.
The integral 2:1 wire purchase system runs from the bottom of the rod around the top sheave and culminates in a free end (made off with a stainless steel thimble eye) to which a kicking strap (or vang) tackle should be connected.
The 180° turn in the wire part of the Rodkicker doubles the power of the vang, and by the same token, reduces the load by 50%.
The Kicking Strap tackle is not supplied as part of the Rodkicker, but you should be able to use your existing kicking strap blocks and line (subject to an adjustment in length) because, due to the integral wire, they should be stronger than the Selden recommendation.
Universal, as well as Selden specific, boom and mast brackets are available if the rodkicker ends do not fit straight on to your existing kicking strap attachment points.
The Jimmy Green Rigging Sales Team are on hand to help you find the correct part number.
A study of the Selden charts below confirms that their recommended specification for the blocks on a normal Kicking Strap is higher than those on a Rodkicker Tackle.
The Selden recommendations are based on a combination of Yacht Length Overall and Righting Moment calculated at 30% of heel.
Righting moment is a measure of a yacht's ability to carry sail and is approximately proportional to displacement.
Selden use righting moment as a major factor in their recommended specifications right across the spectrum of rigging applications and hardware, so it is extremely useful to know the answer for your own yacht.
You will need to enter your Beam in mm, Draft in mm, Displacement in kg, Ballast in kg, whether it has a bulb or wing keel and the number of crew members normally on the rail:
Selden Righting Moment Calculator
Select the correct Rodkicker size by Maximum Righting Moment in kNm (or Displacement in tonnes)
There are two sizing charts: 1. Fractional Rig and 2. Masthead Rig
1. Fractional Rig| Rodkicker Model | Maximum Righting Moment | Maximum Displacement | Current Selden Boom Section | Previous Selden/Kemp Boom Section | Boom Height | Minimum Length | SWL |
|---|
| Type 05 Standard | 12.5kNm | 2.5 tonnes | B087-B120 | 86/59-111/75 | < 900mm | 1150mm | 8kN |
| Type 10 Standard | 25kNm | 5 tonnes | B087-B152 | 86/59-111/75, 128/90 | ≤ 1100mm | 1360mm | 12kN |
| Type 10 Long | 25kNm | 5 tonnes | B087-B152 | 86/59-111/75, 128/90 | > 1100mm | 1670mm | 12kN |
| Type 20 Standard | 50kNm | 9 tonnes | B171-B200 | 150/105-189/132, 206/139 | ≤ 1400mm | 1720mm | 18kN |
| Type 20 Long | 50kNm | 9 tonnes | B171-B200 | 150/105-189/132, 206/139 | > 1400mm | 2260mm | 18kN |
| Type 30 Standard | 120kNm | 20 tonnes | B200-B250 | x | ≤ 1800mm | 2200mm | 38kN |
| Type 30 Long | 120kNm | 20 tonnes | B200-B250 | x | > 1800mm | 2700mm | 38kN |
2. Masthead Rig| Rodkicker Model | Maximum Righting Moment | Maximum Displacement | Current Selden Boom Section | Previous Selden/Kemp Boom Section | Boom Height | Minimum Length | SWL |
|---|
| Type 05 Standard | 15kNm | 3.9 tonnes | B087-B120 | 86/59-111/75 | < 900mm | 1150mm | 8kN |
| Type 10 Standard | 35kNm | 6 tonnes | B087-B152 | 86/59-111/75, 128/90 | ≤ 1100mm | 1360mm | 12kN |
| Type 10 Long | 35kNm | 6 tonnes | B087-B152 | 86/59-111/75, 128/90 | > 1100mm | 1670mm | 12kN |
| Type 20 Standard | 70kNm | 11 tonnes | B171-B200 | 150/105-189/132, 206/139 | ≤ 1400mm | 1720mm | 18kN |
| Type 20 Long | 70kNm | 11 tonnes | B171-B200 | 150/105-189/132, 206/139 | > 1400mm | 2260mm | 18kN |
| Type 30 Standard | 160kNm | 25 tonnes | B200-B250 | x | ≤ 1800mm | 2200mm | 38kN |
| 160kNm | 25 tonnes | B200-B250 | x | > 1800mm | 2700mm | 38kN |
Boom Height is denoted and measured as per XBH, see image below
SWL = Selden Safe Working Load
There is more detailed Selden information on sizing including comprehensive charts on normal, hard and extra hard gas springs, see below.
Selden Rodkicker Information and Size Guide
If you are still uncertain which model and/or gas spring is best suited to your yacht, please contact the Jimmy Green Rigging Sales Team with your yacht details for a reassuring check by the Selden experts.
