OUTSIDE VS: INSIDE TAIL-ENDUpdated a year ago
Usually the longer and/or the more extended the boom the softer it gets. Problem is that the bigger the sail (= longer boom) gets the more crucial the boom stiffness becomes for the sail performance and wind range (see above CARBON VS. ALUMINIUM).
Since you pull with your back-hand when accelerating or pumping or when a gust hits your sail the tail-end section is the most crucial part for the overall stiffness of your boom. All booms nowadays either come with an inside- or outside tail-end.
OUTSIDE TAIL-END
Invented by the DUOTONE team back in 2007. Here the tail-end tubes slide OVER the boom body.
The larger tail diameter/cross-section increases the overall stiffness of your boom by minimum 30%. Plus in contrary to inside tail-ends the boom stiffness isn't affected when you extend the boom length.
Nevertheless the outside tail-end has 2 limitations:
a. When changing the boom length you need to move the adjustment locking system alongside the tail-end tube. This makes it less comfortable and slower to operate.
b. With the usual 50 cm of adjustment range an outside tail-end requires a minimum boom length of 180 cm. Any shorter and your back-hand may end up being positioned on the (thick) tail-end tube.
INSIDE TAIL-END
This is the classic version to adjust your boom length since the beginning of booms becoming variable in length. Here the tail-end runs INside the boom body.
Advantages are:
> Works for any size/length of boom as the tail-end will never interfere with your back-hand.
> The adjustment locking system is fixed to the boom body. This way it's easier, faster and more comfortable to adjust the boom length.
The only disadvantage is the reduced stiffness which gets worse the further you extend your boom. Usually the tail-end angle is parallel to the boom body angle (in the back). This way you have the least friction between the 2 parts making the tail-end slide very easily inside the boom body. This makes it very comfortable to adjust the length, sometimes up to a point that you can hear a certain "click-clack" when you're heavily "wobbling" your boom.
The only way to increase the boom stiffness featuring an inside tail-end is to generate a certain "pre-tension" in the boom. To do so the angle of the tail-end gets increased so that it doesn't match with the boom body anymore. With this pre-tension you increase the boom stiffness but at the same time remarkably reduce the comfort and ease of use when adjusting the length (therefore only used on PLATINUM 170).
