Rigging boat for dry dock lift.

[Gonefishing85]

Hello. I need some data and direction. Im looking to set my 1988 Trophy 2459 so I can lift it off the trailer and put it into the Ocean from an elevated dry dock. Belly straps are not an option. I'll add several photos for reference.

I have to have 4 attachment points on the boat. Rope will be attached to these points with shackles. The ropes will then attach to the crane hook at a single point.

my 2 main concerns are...

1. I need to address the crushing effect of the ropes going from 4 points to one point. Ideally, I don't want to fold my boat in half.

2. The strength of the fiberglass. I.E. how thick would I have to build up the fiberglass in order to prevent 4- 1/2" to 1" bolts at each attachment point from ripping through it? I will have a backing plate so im not worried about the bolts being pulled out. My concern is the bolts actually cutting through the fiberglass.

I estimate the hull fiberglass to be about 1/4" thick at most. I don't believe that would work without further build up. I estimate the boat fully loaded will at maximum be 8k pounds. This includes the boat, gear and passengers which must be lowered onboard the vessel.

Attached is a photo of a trophy 2459, examples of the attachment points I will need and a photo showing the launching crane.

 

[Scott Danforth]

they lift thousands of boas per day with straps, why do you not want straps?

you wont be able to lift it from the gunwales

give you a hint, the transom tie downs go thru the transom and have reinforcing plates start with that thickness...... and tie it all the way down to the stringers/deck/transom

if you are going to pick like shown you will tear out your gunwales and remove your cap

our company makes marine cranes and yacht tender cranes. we deal with this all the time.

at a minimum, you will need lifting cleats and anchor turn buckles that go down to the stringers. accon makes lifting cleats, they are not cheap. a boat your size would need 4 of the 10# lifting cleats, and custom hardware below deck

Lifting Hardware

Shop Lifting Hardware at Accon Marine. Superior Marine Hardware and Accessories.

shop.acconmarine.com

also give you a hint, if your going to lift from above, you start adding reinforcing into the stringer tubs and under the deck when the boat is still in the mold.

 

[racerone]

?----What do local rules say about lifting with people on board ?----Location ?

 

[Scott Danforth]

HOP (Handling of Personnel) is a whole other class of product.

 

[racerone]

But he says the boat has to be lowered / lifted with people onboard.-----Insurance / liability might be an issue to think about.

 

[Scott Danforth]

to be lifted with people on board, you need to have HOP compliance (which requires Lloyds registry witness testing)

and since there were many changes to LAME for the HOP rules, I do it for a living, and I wouldnt do it on my own.

 

[Gonefishing85]

they lift thousands of boas per day with straps, why do you not want straps?

you wont be able to lift it from the gunwales

give you a hint, the transom tie downs go thru the transom and have reinforcing plates start with that thickness...... and tie it all the way down to the stringers/deck/transom

if you are going to pick like shown you will tear out your gunwales and remove your cap

our company makes marine cranes and yacht tender cranes. we deal with this all the time.

at a minimum, you will need lifting cleats and anchor turn buckles that go down to the stringers. accon makes lifting cleats, they are not cheap. a boat your size would need 4 of the 10# lifting cleats, and custom hardware below deck

Lifting Hardware

Shop Lifting Hardware at Accon Marine. Superior Marine Hardware and Accessories.

shop.acconmarine.com

also give you a hint, if your going to lift from above, you start adding reinforcing into the stringer tubs and under the deck when the boat is still in the mold.

Its not a preference issue. The port won't lift with the cradle type strap set up. Also the port exclusively lifts with passengers on board. No other option. Its been the standard procedure here for many years. Thousands of boats use this crane each year. Many of them are fiberglass hull which have been fit with lifting points. Im just at a loss of how to make it work.

 

[Gonefishing85]

I suspect the fixed points rater than running straps under the hull, my be due to legal requirements.

 

[alldodge]

I don't see how to protect the boat without spreader bars

 

[racerone]

There is no way that I would sit in a boat being lifted as per pictures in post #1.---If I had to do that lifting.-----I would fabricate HEFTY lifting points that go through the rear deck to the transom.-------And through the front deck to the hull !!

 

[Gonefishing85]

There is no way that I would sit in a boat being lifted as per pictures in post #1.---If I had to do that lifting.-----I would fabricate HEFTY lifting points that go through the rear deck to the transom.-------And through the front deck to the hull !!

Go to the 4:30 mark on the video and watch it from that point forward. I understand the hesitancy but around here, it is done day in and day out. And it is all up to legal standards and regulations.

 

[racerone]

Looks like a lift point through the front deck.-----And 2 lift points to the transom.

 

[Gonefishing85]

Looks like a lift point through the front deck.-----And 2 lift points to the transom.

For that particular boat, yes. However, it is aluminum and a couple thousand pounds lighter than what I'm working with.

I have been looking at the accon lift cleats that were mentioned earlier. They make a kit called "Complete Extra Large Lift Eye Assembly". It is rated for 12k pounds. Being as my boat would be an absolute maximum of 8k on the lift, Im curious if those would work in a 3 point configuration by using the existing locations of my bow and stern eyes. It would cost a bit more to go that way but it would also require less time and modifications.

My original plan was to go with attachment points like on the Parker in the photos I attached with my original post. What I was going to do was build up the fiberglass on the inside of the hull in the areas where the brackets would be installed. I was going to make a flat "pad" then use a large backing plate about 1'x1'.

As I previously said, im not worried about the attachment bolts being pulled out. What I don't know is how thick the fiberglass would need to be in order to assure the weight of the boat doesn't cause the bolts to tear through the fiberglass. Think saw cutting a peice of plywood.

 

[dingbat]

My boat is designed to be lifted that way using two, thru-bolted eye hooks on the transom and the bow hook

 

[racerone]

Now we are looking at some proper well thought out lifting gear. !!-----Thanks for posting those pictures Dingbat.

 

[racerone]

Where I worked all lifting gear was subject to annual inspection !----Shackles , eyebolts and slings.------Some common lifts were 35 tons ( electric motors ) some lifts up to 200 tons as well.-----Required 2 cranes for those big lifts !----Regular lifts involved a machine likely worth $5 or 6 million to replace.----We worked carefully.

 

[Gonefishing85]

My boat is designed to be lifted that way using two, thru-bolted eye hooks on the transom and the bow hook

View attachment 327919

View attachment 327918

What boat is that?

 

[dingbat]

What boat is that?

Grady White boats
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