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Another lifting an FT10 idea


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#1 PNWsailorGuy

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Posted 20 May 2011 - 10:16 PM

Is it possible to use the engine mount where the engines slides into the water as the aft triangulated lifting point? This seems like a strong part of the boat. New hinges would have to be installed that would allow the engine hatch cover to be easily removed so that the webbing from the lifting point would be able to angle toward the hook of the crane.

So the questions are:
  • Will the engine mount support the triangulated weight?
  • Is there a hinge that can be installed so that when the hatch cover is lifted it can easily be removed from over the engine to expose the lifting points on the engine mounts?

Can it be done?

If this line of lifting has been explored please let me know.

PNWSG

#2 Christian

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Posted 21 May 2011 - 01:25 AM

Why not just add a lifting eye to the transom - I remember the previous builder of the boat being very proud that you could hang the Tiger by the tail

#3 owlslick

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Posted 21 May 2011 - 03:52 PM

going to a transom lifting point the angle of the bridle would be too shallow, allowing rotation, if the keel lifting point is used. A steep angle would be better for control. If the hull is going to be supported by the keel bulb, then the amount of weight should be minimal ( enough to keep the boat from rotating / transom dropping ) as the boat is lifted. ( some are using a few water filled 5 gal jugs on the bow for balance ) I'm thinking the the fairleads moved aft on the jib track should be strong enough and allow for a good angle to the keel lift point to keep the transom from rotating down. ( The fairleads and jib track are rated for a few thousand pounds of load while the load to balance would less than a couple hundred pounds )

#4 extrad

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Posted 21 May 2011 - 10:22 PM

going to a transom lifting point the angle of the bridle would be too shallow, allowing rotation, if the keel lifting point is used. A steep angle would be better for control. If the hull is going to be supported by the keel bulb, then the amount of weight should be minimal ( enough to keep the boat from rotating / transom dropping ) as the boat is lifted. ( some are using a few water filled 5 gal jugs on the bow for balance ) I'm thinking the the fairleads moved aft on the jib track should be strong enough and allow for a good angle to the keel lift point to keep the transom from rotating down. ( The fairleads and jib track are rated for a few thousand pounds of load while the load to balance would less than a couple hundred pounds )



Surely the object of pulling the lifting sling/cable aft relative to the hull is to ensure that the lifting point is above or aft of the CoG of the boat so that the transom is higher than the bow to ensure that the lifting cable doesn't foul the mast head. The "aft pulling" string should be secured as far aft as possible as this reduces the load on the string.

Alternatively if you can't actually pull the lifting cable aft, then fixing the "aft lifting" string as high up the lifting cable as possible and as far aft as possible reduces the load on it.

#5 Ship o' Fools

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Posted 22 May 2011 - 12:17 AM

going to a transom lifting point the angle of the bridle would be too shallow, allowing rotation, if the keel lifting point is used. A steep angle would be better for control. If the hull is going to be supported by the keel bulb, then the amount of weight should be minimal ( enough to keep the boat from rotating / transom dropping ) as the boat is lifted. ( some are using a few water filled 5 gal jugs on the bow for balance ) I'm thinking the the fairleads moved aft on the jib track should be strong enough and allow for a good angle to the keel lift point to keep the transom from rotating down. ( The fairleads and jib track are rated for a few thousand pounds of load while the load to balance would less than a couple hundred pounds )


I think your math may be off on this - though I am no expert. I amount of weight people are loading on the bow is at least 200 lbs which is 15 ft forward of the center of gravity, so the force closer to the cg is much higher.

It seems to me that if you have 200 lbs on the bow (which is about/at least 15 feet forward of the center of gravity) the torque force you are creating is 3,000 ft-lbs of torque. (Force x lever arm = torque) If you were to lift just 3 ft behind the cg then the lifting force would be 1,000 lbs. (3000 ft-lbs/3 ft = 1000 lbs.) The further back the lifting point, the less vertical force required.

#6 Christian

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Posted 22 May 2011 - 02:15 AM

going to a transom lifting point the angle of the bridle would be too shallow, allowing rotation, if the keel lifting point is used. A steep angle would be better for control. If the hull is going to be supported by the keel bulb, then the amount of weight should be minimal ( enough to keep the boat from rotating / transom dropping ) as the boat is lifted. ( some are using a few water filled 5 gal jugs on the bow for balance ) I'm thinking the the fairleads moved aft on the jib track should be strong enough and allow for a good angle to the keel lift point to keep the transom from rotating down. ( The fairleads and jib track are rated for a few thousand pounds of load while the load to balance would less than a couple hundred pounds )



Damn you are a little slow - it was a joke..................


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