Adding mainsheet block to pre-72 fish

[jamesg]

I want to add a mainsheet block to my ancient Sunfish. I have the hardware, but am wondering about attachment. Should I simply mount it through the lip of the cockpit with an aluminum backing plate? Will this be strong enough? Thanks!

 

[Wavedancer]

Yes on both accounts.

 

[jamesg]

Done!

Behold, the $6 Ace Hardware mainsheet block!

 

[surfski]

Nice one ! now did you lay a little 4200 in there to seal/bed things up ?

 

[jamesg]

Used life seal, not 4200. I don't think 4200 would add much to a 1/4" SS u-bolt backed by a 3/4" strip of brass. No water will be getting in, though.

 

[Wavedancer]

A new competitor for Mr. Harken!


Seriously though, tell us, after a few outings, how your 'invention' works in practice.

 

[matias]

Done!

Behold, the $6 Ace Hardware mainsheet block!

Have you tried using a ratchet block?

 

[jamesg]

Not yet; only had the boat out once, last weekend. If the poor man's mainsheet block (PMMB) proves unsatisfactory, though, I'll drop the $40 on a Ronstan or Harken.

 

[Wayne]

Used life seal, not 4200. I don't think 4200 would add much to a 1/4" SS u-bolt backed by a 3/4" strip of brass. No water will be getting in, though.

What significant difference have you experienced we should be aware of ?

Life Seal . . . . . . . . . . . . 3M 4200

. . . . . .

Primary Component
Polyurethane . . . . . . . . . . . Polyurethane

Lap Shear
240 psi . . . . . . . . . . . . 258 psi

Tensile Strength
290 psi . . . . . . . . . . . . 300 psi

Cartridge Price
(Jamestown Dist)
$11.42 . . . . . . . . . . . . $11.64



​

 

[jamesg]

None whatsoever, just didnt think there was any point in using the marginally stronger adhesive on a brass-backed u-bolt.

 

[Wayne]

Not yet; only had the boat out once, last weekend. If the poor man's mainsheet block (PMMB) proves unsatisfactory, though, I'll drop the $40 on a Ronstan or Harken.

Your $6 idea should work fine. Before someone borrowed the ratchet block idea for easing arm strain from big boat spinnaker and jib control systems, these straight pull sorts of arrangements were all used successfully. I do like your mini-stand-up spring too.

 

[Wayne]

None whatsoever, just didnt think there was any point in using the marginally stronger adhesive on a brass-backed u-bolt.

Ah, I see ... thanks. Considering the task is just to seal off the edges of the freshly drilled holes either should be fine. I think with the polyurethane variety caulks a little more adhesive strength than a silicone caulk has just comes with the territory. It's the extra adhesive strength caulks like 3M 5200 you want to choose wisely where they get applied.

 

[Fred P]

The purpose of a main sheet block is to gain some friction for the main sheet while holding it steady and to still make it easy to sheet in when necessary. Thus, the ratchet block was born. The $6 Ace block lacks the friction component (and I hope it's stainless steel).
Go for the Harken every time.

Fred

 

[surfski]

to each his own , i am a "hook" person at present and it works just fine , keepin it old school !

 

[Wayne]

It's simply a matter of preference . . .

.

 

[surfski]

Thanx Wayne , once again clear and consice !

 

[jamesg]

Have had the boat out twice and the Ace block has worked fine both times. No binding our fouling of any kind.

 

[tynwald]

I once lost my ratchet block (somehow the ring ding worked loose), so went to the "Ace solution" for awhile. Works, but the ratchet effect is very helpful if you're trying to keep a fixed trim on the mainsheet for a long time (especially in a blow). Ultimately, broke down and bought another Harken block (but I keep my "Ace in the hole" as a back-up!).

 

[ivy]

It's simply a matter of preference . . .

.

There is one more advantage to add to your diagram for the latter three images. Using the block/hook on the deck allows the sail to be oversheeted, putting a bend in the boom. This bend will take the draft out of the sail, reducing power and drag in heavy air.

This is more or less the same function that the backstay performs on a fractional rig.

 

[NightSailor]

Used life seal, not 4200. I don't think 4200 would add much to a 1/4" SS u-bolt backed by a 3/4" strip of brass. No water will be getting in, though.

No point in bedding that for water intrusion. Bedding in this case will just protect the finish of the deck and prevent the U-bolt from moving around--which is not likely if securely fastened.

While it is a cheap solution, a ratchet block will save your hands and arm on a windy day. I'd rather have the old bronze hook than that block because that holds the load well. [no offense]