Question on Two Versions of the Mast Raising Systems on Horizon Cat?

[Roland of Macatawa]

Some comments about the MastendrPlus system from the sailor of a SunDayCat:

My SunDayCat is a 2012 model and has the MastendrPlus system. It is my understanding, subject to correction if mistaken, that the SunDayCat has always been equipped with the MastendrPlus system, and that the MastendrPlus system was available on the SunCat only as an option.

The height of the integrated gin-pole is determined by the horizontal distance from the mast hinge to the bow of the boat. This is because it is necessary for the block-and-tackle to be aligned perpendicularly to the gin-pole when the mast is upright. This brings the end of the gin-pole directly above the block-and-tackle's anchor point on the bow of the boat.

My block-and-tackle has a 4:1 purchase. That does not give enough mechanical advantage force multiplication to lift the mast off of its cradle. Certainly, a longer gin-pole could provide more leverage, but only if the block-and-tackle's anchor point could also be brought further forward.

I raise the mast this way. Standing about in the center of the cockpit, I manually raise the mast off of its cradle and rest it on my shoulder. From there I manually raise it with the line of the block-and-tackle (there is no winch). I do not pull on the line hand-over-hand. Rather, I hold the line and lean back to use my body weight to pull the line. (Note that the line is pulled through a locking friction clutch so it will hold position if the grip onto the line is released.) As the mast rises, it tends to wander off center, especially if the trailer is not perfectly level side to side. I use one hand to guide the mast to center by pulling or pushing on a side stay, as necessary. When the mast is about 80% raised the side stays are losing their slack and hold the mast near-center. Then, because the mast is now nearly upright, I pull hand-over-hand until the side stays go taut and the mast becomes centered. Then I pull as hard as I can, with both hands and my body weight, to apply tension to the forestay. Note that the tension in the forestay is limited by the amount of force I can apply to the line through the block-and-tackle. You can feel when the hinge is fully closed into its upright position because the pulling force opposition rises dramatically. (The locking lever of the SunCat's Mastendr system may apply greater forestay tension than what pulling on the SunDayCat's block-and-tackle's line can apply to the forestay. So, the MastendrPlus system may provide greater convenience at the loss of forestay tension.)

In my opinion, others may disagree, it is necessary to apply sufficient tension to the forestay so that the hinge stays fully closed under sailing conditions. This ensures that the bending, compression, and shear loads within the mast are carried through the hinge by vertical contact and the hinge collars and not by the hinge ears and pivot pins. An implication of this is that you ought not over-tension the side stays making them act to pull the hinge back somewhat open. I have adjusted my side stays so that I can just get the hinge fully closed in my final pull on the block-and-tackle's line.

Although this discussion is about raising the mast, the MastendrPlus system is also helpful lowering the mast under control.

Bruce, if I recall correctly, the Boomtendr system is a scheme where for trailering the boom is folded up along the mast and then the boom and mast together are lowered to the mast cradle. Not sure how the sail is flaked between the boom and mast or how the folded-up boom is fastened to the mast. Perhaps an owner can enlighten us.

Regards, Roland

[Boat-in]

Some comments about the MastendrPlus system from the sailor of a SunDayCat:

My SunDayCat is a 2012 model and has the MastendrPlus system. It is my understanding, subject to correction if mistaken, that the SunDayCat has always been equipped with the MastendrPlus system, and that the MastendrPlus system was available on the SunCat only as an option.

The height of the integrated gin-pole is determined by the horizontal distance from the mast hinge to the bow of the boat. This is because it is necessary for the block-and-tackle to be aligned perpendicularly to the gin-pole when the mast is upright. This brings the end of the gin-pole directly above the block-and-tackle's anchor point on the bow of the boat.

My block-and-tackle has a 4:1 purchase. That does not give enough mechanical advantage force multiplication to lift the mast off of its cradle. Certainly, a longer gin-pole could provide more leverage, but only if the block-and-tackle's anchor point could also be brought further forward.

I raise the mast this way. Standing about in the center of the cockpit, I manually raise the mast off of its cradle and rest it on my shoulder. From there I manually raise it with the line of the block-and-tackle (there is no winch). I do not pull on the line hand-over-hand. Rather, I hold the line and lean back to use my body weight to pull the line. (Note that the line is pulled through a locking friction clutch so it will hold position if the grip onto the line is released.) As the mast rises, it tends to wander off center, especially if the trailer is not perfectly level side to side. I use one hand to guide the mast to center by pulling or pushing on a side stay, as necessary. When the mast is about 80% raised the side stays are losing their slack and hold the mast near-center. Then, because the mast is now nearly upright, I pull hand-over-hand until the side stays go taut and the mast becomes centered. Then I pull as hard as I can, with both hands and my body weight, to apply tension to the forestay. Note that the tension in the forestay is limited by the amount of force I can apply to the line through the block-and-tackle. You can feel when the hinge is fully closed into its upright position because the pulling force opposition rises dramatically. (The locking lever of the SunCat's Mastendr system may apply greater forestay tension than what pulling on the SunDayCat's block-and-tackle's line can apply to the forestay. So, the MastendrPlus system may provide greater convenience at the loss of forestay tension.)

In my opinion, others may disagree, it is necessary to apply sufficient tension to the forestay so that the hinge stays fully closed under sailing conditions. This ensures that the bending, compression, and shear loads within the mast are carried through the hinge by vertical contact and the hinge collars and not by the hinge ears and pivot pins. An implication of this is that you ought not over-tension the side stays making them act to pull the hinge back somewhat open. I have adjusted my side stays so that I can just get the hinge fully closed in my final pull on the block-and-tackle's line.

Although this discussion is about raising the mast, the MastendrPlus system is also helpful lowering the mast under control.

Bruce, if I recall correctly, the Boomtendr system is a scheme where for trailering the boom is folded up along the mast and then the boom and mast together are lowered to the mast cradle. Not sure how the sail is flaked between the boom and mast or how the folded-up boom is fastened to the mast. Perhaps an owner can enlighten us.

Regards, Roland

Wow!

Richard, thank you for the very well written description.

I can now visualize the operation of the system.

Big thanks,
Dan

[bruce]

Always good to hear from you, Roland. Your engineering background shows .

I've been following the Com-Pac catboat line since 2010 when I was looking for a boat. I would have guessed the Mastendr Plus was later than 2012, but clearly I would be wrong.

I haven't heard of the hinge opening under sail, although you may have mentioned it and I didn't pick up on it. The hinge, compared to the Marshall Marine hinge for example, is relatively under-engineered, but I've heard of few if any failures. The curved pin, if used, would provide some reinforcement. Neither the SC or the PC carry a lot of sail for their size compared to other catboats. I haven't noticed any opening of the hinge on my PC under any conditions, using the stock wire cable forestay and Highfield lever. I'd consider stretch in the Mastendr Plus line as a possible source of the hinge opening. Not sure what line they used, but there may be newer lower-stretch lines that could be beneficial. Certainly if the shrouds are over-tensioned and the hinge doesn't close is a problem.