Lift points

[msidd]

1957 Lyman Runabout 15" recommended lift point with outboard attached.

[wizbang 13]

One of those eyebolts that screw into the top of the flywheel...be my first choice.
Lift the engine, boat will follow. Pick the bow from the tow bolt.
...if that is wha cher axing

[Ian McColgin]

Most uses get the boat in and out by trailer. Have see some marinas that provide dry storage on racks, in and out by specialized fork lift. Some especially grand places have a roof and walls and a lift to get the boat out.

If you feel you must lift by crane and don't trust slings, or if you're thinking of building davits so you can carry it on your 100' motor yacht, start by knowing the loading weight at bow and stern. If no scale big enough, make an 11' lever (so you can have 10:1 multiplier) and pry the boat up a little. A first class or second lever will work and you can press the lever holding a scale to see how much force it takes to more her.

Most Runabouts have a towing eye just above the waterline. Check that it's in good condition, properly bolted through the stem, and robust enough to take the load plus a generous safety factor. It would make sense to make a lift sling here so it can embrace the bow. Padding required.

For the stern, eyes through the transom as far out as makes sense, maybe half way up, with decent length chainplates so the strain does not split the transom. Bolted and backed.

And how's this for the Mothership:

[Thad]

The problem with the towing eye besides it's low position is it is set for tension not sheer, using it to lift up would tend to split the stem. Lifting eyes at the bow would normally be placed in the middle of the fore deck, like the mooring cleat, but connected through the keel at the base of the stem. At the stern, lifting the transom with a bridle between two high through eye bolts would lift the engine and the hull.

[wizbang 13]

Yes, but a 15 foot ob boat should weigh very little in the bow .Not like an inboard boat .

[Thad]

Might almost balance on the transom? With some outboards it might, almost.

[Rich Jones]

You're only about 45 minutes from me.
In non-Covid times, I'd offer to come over and help out with whatever you've got going on.
Perhaps next summer!

[msidd]

You're only about 45 minutes from me.
In non-Covid times, I'd offer to come over and help out with whatever you've got going on.
Perhaps next summer!

Thanks Rich, where are you located?
I am planning on painting the hull and repairing some damage on the forekeel in the spring, so getting it off the trailer would be very helpful.
I am a newbie with wooden boats and would greatly appreciate any guidance you can offer.
Thanks

[oldsub86]

gantry made of wood 2.jpgGantry made of wood 3.jpggantry made of wood.jpggantries and slings with photos saved from the net over time (from this forum if I am not mistaken)

[wizbang 13]

msidd, yer just trying to get her off the trailer?
Drop the trailer tongue to the ground, (this will lift the stern),block up /or tie up the boat stern /engine where it is at.
Lift the trailer tongue with the screw or a jack, (this will seperate the sten of the boat from the blocking).
Tie the bow up to a rafter or a crossbeam between the bow and tongue,which is probably very light,...release the tie between bow eye and trailer winch...voila...pull the trailer out from the suspended boat .
bruce

[Garret]

Good to see another woodchuck on the forum - welcome! I'm just northeast of Burlington.

Bruce's suggestion is a good one.

A single lift point would be tough. Chris Crafts have 2 - but that's on inboards. A friend who has a Thompson that's similar to your boat used 2 straps hooked to comealongs. If using this method, be sure to put a spreader between the sides of the straps so the hull does not get crushed. Also make sure the upper attachment points are strong enough!

[msidd]

Thanks Wizbang, oldsub86 and Garret, and Rich
Among other things I am a timber frame builder so I know how to lift and move heavy wood objects.
Yum Runner is temporarily housed in a timber frame garage. My intuitive inclination was to use straps, spreaders and the building as structure to lift it off the trailer.
Once off the trailer I need to block it. I plan on blocking under the transom and the forekeel. Keeping the contact as small a footprint as possible so I can repair and paint the hull. After paint and repair, lift again with the straps and paint the area that was missed. Please correct me if this is not a good plan.
Thanks so much
Mitch

[wizbang 13]

Yes it's a good plan...for a 2 ton 25 footer.
Can we get photos of her and the trailer?

[Thad]

And the building.

[msidd]

Thanks All.
MMD is pretty right on about the weight. I have a portable gantry to place just forward of the transom, no need for a spreader. Blocking just under the keel will take all of the weight?
Here is a funny: Dreamed last night that I rolled her over like G&B Marine Railway did to Jonathan Edwards the "Elisa Lee"!! LOL

[Thad]

How the mind keeps working!

[msidd]

yum runner.jpgooops, forgot to attach a photo per request from Wizbang 13.

[msidd]

Tell. me about it! sometimes a burden

[kbowen]

fwiw, industrial lifting straps are not much $ at Grainger, and can be had at loads more than you will never need. Empirical process: with the boat in the water under a crane, lift it just clear of the water and adjust the straps until you find the balance point, if something goes wrong, there will be a splash and no more. If you want to weigh it, rent a dynamometer or make friends with someone who does rock-and-roll truss rigging. The things nowadays broadcast weight by wifi and are only a bit larger than a shackle. My mackinaw weighed 3340 with water ballast empty. The red thing in the photo is a load cell I was able to borrow that was good for 10 tons. Once you find the balance point, talk to people with some engineering chops and put in the lift points.

Ken
IMG_8558.jpg

[kbowen]

Some time ago I posted a method for calculating the weight of a boat on its trailer using a tape measure and bathroom scales. No rentals or cranes involved.

seriously, send me the link. there isn't any pick point on my boat that I can think of but it would mash a bathroom scale

Ken

[oldsub86]

Borrowed from another web site:

Here is the method I use to weigh boats on a trailer without hauling the boat to a commercial scale, which requires two trips for boat and trailer.
It's simple, accurate and will cause bystanders to marvel at your engineering whiz.
The boat stays on the trailer the entire time. Put the scale under the tongue near the end. You can even put a block on the scale to lift the tongue so you can see the dial. Record the weight. Now, slide the boat aft on the trailer 12" to 18". You must measure exactly how many inches you moved it, and record that. With the scale in the same location under the tongue, record the new scale reading. Finally, measure the distance in inches between the trailer axle (wheel centerline) and the point on the tongue where it touches the scale. You have then four measurements:
W1 = first (heavier) scale reading in lbs, W2 = second scale reading in lbs, X = the distance you shifted the boat in inches, C = distance between trailer axle and scale point in inches.
The formula is Boat Weight = C (W1-W2)/X
A couple of notes. The result, like any measurement, is sensitive to the accuracy of the input data. In this case, the most critical is the distance you slide the boat. One inch error out of 12 inches will really make a difference in the result. Slide the boat as far as you can and still have a readable load on the scales. Notice, too, that by subtracting the two scale readings, any constant error in the scale is canceled out.
Note to techies: The formula was derived by taking the sum of the moments around the trailer axle for each case and (since the sum of moments about a stationary object is zero) set the two equations equal to each other and solve for the trailer weight. Things that you don't know, like the trailer's weight and the location of the boat's center of gravity cancel out, leaving just the variables that you can measure, and the boat weight.
I also use another version of this formula for weighing a boat while it is under construction so I don't get a bad surprise when it's finished. You can use two bridged scales and/or a trailer extension to increase the range of weights you can measure. I usually shoot for measurements of about 30-40lbs
for a low end and 250lbs or so for the high end.
In your case I would reverse the order of moving the boat and do it when you next go to the launch ramp so you can move the boat in a partial launch.

[Powerwagon]

Great advice here so far! I use the outboard to lift the aft end of smaller skiffs/runabouts. I have one of those motor locks that slides over the securing screw handles, it forms a cleat. The bracket that holds the motor to the transom is very strong and makes a good lift point.

[Breakaway]

Erring on side of caution, given that my point of view is not standing beside you and your specific boat, I am going to humbly suggest you want to lift an older, lightly-built wood boat from underneath. That probably means straps suspended from a block and fall for a DIY application. But it could also mean blocking or a cradle jacked up incrementally. Would help to know why you need to lift it and how often you need to do so.

Kevin

[kbowen]

The process below is really elegant! However it is dubious in my case; the tongue weight is #430, It's really difficult to slide the boat on the trailer unless it's good and slimy with algae, and it's a dual axle trailer, so exactly where is the center point of the suspension system?? All bickering aside, I am definitely going to try it when things warm up to compare with my other figures. Thanks!!

Ken

Borrowed from another web site:

Here is the method I use to weigh boats on a trailer without hauling the boat to a commercial scale, which requires two trips for boat and trailer.
It's simple, accurate and will cause bystanders to marvel at your engineering whiz.
The boat stays on the trailer the entire time. Put the scale under the tongue near the end. You can even put a block on the scale to lift the tongue so you can see the dial. Record the weight. Now, slide the boat aft on the trailer 12" to 18". You must measure exactly how many inches you moved it, and record that. With the scale in the same location under the tongue, record the new scale reading. Finally, measure the distance in inches between the trailer axle (wheel centerline) and the point on the tongue where it touches the scale. You have then four measurements:
W1 = first (heavier) scale reading in lbs, W2 = second scale reading in lbs, X = the distance you shifted the boat in inches, C = distance between trailer axle and scale point in inches.
The formula is Boat Weight = C (W1-W2)/X
A couple of notes. The result, like any measurement, is sensitive to the accuracy of the input data. In this case, the most critical is the distance you slide the boat. One inch error out of 12 inches will really make a difference in the result. Slide the boat as far as you can and still have a readable load on the scales. Notice, too, that by subtracting the two scale readings, any constant error in the scale is canceled out.
Note to techies: The formula was derived by taking the sum of the moments around the trailer axle for each case and (since the sum of moments about a stationary object is zero) set the two equations equal to each other and solve for the trailer weight. Things that you don't know, like the trailer's weight and the location of the boat's center of gravity cancel out, leaving just the variables that you can measure, and the boat weight.
I also use another version of this formula for weighing a boat while it is under construction so I don't get a bad surprise when it's finished. You can use two bridged scales and/or a trailer extension to increase the range of weights you can measure. I usually shoot for measurements of about 30-40lbs
for a low end and 250lbs or so for the high end.
In your case I would reverse the order of moving the boat and do it when you next go to the launch ramp so you can move the boat in a partial launch.

[Garret]

I don't think the trailer/scale method will work with a double axle trailer, as it's counting on a single fulcrum point (the axle in a single axle trailer).

[Garret]

I don't think the trailer/scale method will work with a double axle trailer, as it's counting on a single fulcrum point (the axle in a single axle trailer).

My bad - please see Michael's post.