Snatch block physics help pls

[bigdogg1]

At some point in the future, I will likely install a Sherpa winch but that is down the road.

For my immediate needs, I would like to install a snatch block to double the line to pull my boat up.

Total load is about 9k, 4 x 14’ of carpeted bunks, hand winch loaded with 13k rated amsteel. Have brought it in by fully sinking trailer and gearing winch to low sprocket for last 4’. It works but I think a snatch block will absolutely help.

I have enough Amstel loaded to return back. Will the added pulley change the load on the line?

Greggs sells a 7800# pulley and hook rated for Dutton Landon electric winches. Will this suffice?

I know the retrieve time will double but will the amsteel rating and Gregg’s block rating be sufficient?

Thanks!

 

[Flashman]

Putting a block on the boat, running the line from the winch, through the block and doubling the line back and securing the free end to the post very near the winch will nominally reduce the force in the line by half compared to attaching directly to the boat.

Is it strong enough, can't tell. Total load is much less than the weight of the boat. Actual load is unknowable unless you put a load cell on the line. The hook and winch are likely the weakest parts of the system, assuming the line is in ideal condition. Which one will fail first, no way to know.

I would be more interested in if you have enough room between the winch and bow eye for the block to get the boat all the way up to the bow roller/support.

 

[Loghauler]

A one pulley block or two pulley ?
Lol they get really slow
My 2000lbs boat can be a good crank if I don’t wet the runners and it’s a steep ramp
I’ve seen other materials on the runners would it help ?
The block should be a quick fix if it fits but electric winch is the smart and final fix
Just pay attention to where you attach the free end of the rope as it could change the angle of the pull above the winch it will lift below the winch it will add weight to the nose of the boat on the runners keep it straight as possible or above the winch as long as no interference and if concerned about breakage hang a jacket over the line so it takes the energy of the breakage
But I’m sure you’ll be fine if you expect to pull the dead weight of your boat good luck at most it’s a fraction of total weight

 

[Max123]

A few ways to approach the problem that are worth considering:

Installing the snatch block isn't ideal, because it likely won't allow you to pull the boat all the way up to the bow stop on the trailer. Likewise, you only want the snatch block to act as a reduction gear for the last few feet of the pull - you want speed for the first part of the pull, power for the final part. Snatch block is likely going to require a bunch of messing around with the rigging at the ramp. Hard to beat the simplicity of a 2 speed winch.

Before playing with a snatch block, I'd suggest trying a few things first: #1, check how much clearance you have between boat and trailer - then lower your bunks as much as possible so the boat floats easier. Your bunks may have just been setup too high. #2, confirm that your current winch height is set correctly and you aren't pulling the bow downward - this adds friction and reduces the effectiveness of the winch. This can be a bit hard to tell as the angle of the pull changes as the boat goes from floating to sliding. #3, add bunk slides - dramatically reduces sliding friction and will be an improvement regardless of what you do next.

You may also want to consider a hybrid trailer system that has short bunks in the rear and rollers in the front.

In the end - maybe more force is the answer - Fulton makes a 10k electric winch...

 

[TMan]

Ever consider putting UHMW strips on your bunks? Then when you have the night right. You can drive on and skid up a ways. Then winch the rest. The roller idea isn't that bad either. I think if you use a block you will have to crank like crazy to only go half the distance.

 

[TMan]

Height right

 

[Squire]

I second the hybrid system with rear bunks and rollers up front. My boat weighs under 6,000 lbs and it was just about impossible to drag it up the bunks to the winch post without fully floating it there. I added two rollers up front and it made a huge difference.