S4LT R3- Joint mast foot- rubber joint M10 / M8

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Product Overview

The R3-Joint (Rope-Reinforced Rubber - Joint) mast foot rubber joint from S4LT has an aramid safety line (Kevlar) that runs through the core. The breaking load of the aramid tendon is approx. 200 kg.

The R3 joint has an M10 and M8 thread. The dimensions correspond to those of the rubber joints previously available on the market. The R3 joint is therefore compatible with previous systems and is installed as standard in the S4LT 211 Base.

Available in: M10 / M8 & M10/10

The 211 Base only works with an R3 joint M10 / M8 rubber joint! Conventional rubber joints do not work due to the lack of screw holes on the head of the rubber joint.

R3 - Joint stands for Rope-Reinforced-Rubber-Joint and, in simple terms, means that the safety line runs in the core of the rubber joint. Should the rubber joint ever bless the temporal, the board and sail still remain securely connected via the built-in aramid tendon (Kevlar) with a breaking load of approx. 200 kg. Because the tendon is guided on the inside, it also prevents the rubber joint from overstretching if, for example, you cling to the mast of the sail during a wave wash. Another advantage is that there is comparatively little play due to the very short excess length of the tendon of only 5-10 mm compared to the rubber joint. In the event of a break, the function of the joint is better preserved, which increases controllability in contrast to external safety lines.


The R3 joint hinge complies with the existing standard of rubber joints. The rough dimensions are 42mm in diameter with a height of approx. 58 mm and thus correspond to the dimensions of existing "Boge" rubber joints.

Thread Options:
M10 / M8
The M10 / 8 thread option means that the rubber joint is equipped with an M10 thread and an M8 thread on the opposite side. The M10 / M8 version is usually used with so-called 1-bolt mast base systems. From a technical point of view, the S4LT 211 Base works differently than the systems of the competition, but it also uses the version with M10 / M8 thread. A one-piece M10 Europin is provided for the M10 thread. The M8 thread is used to hold an M8 grub screw. To secure against unscrewing, both the Europin and the grub screw are permanently glued with, for example, green Loctite or comparable products.

M10 / M10
The M10 / M10 thread option means that the rubber joint is equipped with M10 threads on both sides. This option is usually used for so-called 2-bolt mast base systems. This means that a mast base plate is screwed to the mast rail using 2 bolts / screws. The mast base plate usually has a mount for the elaborately constructed version of the rubber joint, which is connected to the rubber joint with an M10 screw.

The 211 Base is unique in its patented design. The connection between the mast base plate and the rubber joint is made using a screw connection, for which the R3 joint was specially designed. This means that only R3 joints can be used for the 211 Base. The other way around, however, the R3 joint joint is compatible with other mast base systems with rubber joints from other manufacturers.

Rubber joint equal to Tendon?
Please note that a so-called tendon joint cannot be compared with a rubber joint. These are different systems with different advantages and disadvantages! First of all, a tendon joint cannot be used for a mast base system with a rubber joint. It doesn't work the other way around either!

Tendon vs Rubber Joint:
Mast foot systems with tendon joints are superior to those of conventional mast foot systems with rubber joints in terms of their height. This means that the height of the mast base is up to 20 mm lower.

This means that the fork can be struck 20 mm lower with the same performance. In other words, it means that the surfer can strike the fork 20 mm higher with the same height setting, which shortens the cantilevered length of the mast beyond the boom. The flex in the mast above the boom is reduced, which increases sailing performance. 

Another advantage of the tendon joint is its significantly lower weight, which is due to its narrow design. However, this is associated with the decisive disadvantage of the rubber joint, because the tendon joint is significantly harder with a very small contact area, which leads to an undamped power transmission. A mast base with a rubber joint should therefore always be used in tough bump and jump conditions.

The 211 Base, on the other hand, manages the balancing act, so that it combines the advantages of both systems!

Heavy-duty black anodized T6 aluminum thread holder connected by a highly flexible aramid rope with a breaking load of approx. 200 kg. Metal thread in injection molding with PA6 (polyamide) plastic coated. EDPM rubber coating.

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