Davit & Lifeboat c. 1950 by FreekS - ~1:10 - RADIO

[FreekS]

This winter I’m working on a “grandfather” repair and renewal project.

 

My grandfather was shipbuilding engineer, and was drafted in WW1, spending the war in neutral Netherlands on one of the fortresses of the defence of Amsterdam. That’s where my last project came from. 

From the 1920s until the end of WW2 he worked in Dutch East Indies (Indonesia) for a shipping company. In 1947 after repatriation to Netherlands he filed a patent on a method to launch a lifeboat from a davit through a clever use of a pivot. Two crewmembers each rotated a handle over 180 degrees, which swings out the lifeboat, descending slightly under its own weight. Then lines are slipped to defend it to the sea.

 

To help him sell the patent, he had a demo model built, published an article in a trade journal, and even made a “cartoon movie” from a set of cards to show the operation. I think about a dozen ships were equipped with the system.

 

The demo model survived the past 75 years or so, but was in somewhat of a state when I received it from a cousin before Xmas. The boat is solid. Just needed a paintjob but is unsuitable for radio control.
 

My plan has three phases

- repair the model

- build a RC controlled new lifeboat to be launched from it

- possibly make the Davit RC as well

 

the repair was fairly straight forward, involved re-soldering the brass and copper past, new paint job and polishing up the blocks and brass parts.

in the last photo, the solid wood boat is half painted, I decided to make a new boat using “plank on frames”. The new boat will be slightly shorter with room for a rudder, and will have a prop obviously.

 

To obtain a plan of the frames, I marked out frames on the keel of the boat model, and used a home made measuring device to measure out the shape of each frame. 

from that I drew the frames on a 7mm pine plank, and the keel on another one (slightly shorter and with opening for the prop).

also the planks themselves were sawed from pinewood, and I’ve just started mounting the frames and keel on a build plank for planking.  TBC…

[FreekS]

Here is the frames on the build plank, and the start and finish of the planking. 
 

Lots of sanding is next, and coating with epoxy 

 

[FreekS]

After first sanding of the outside I’ve cut the boat off it’s build plank to sand the inside. Surprised to weigh in at only 200 grams! The planks are only 2 mm thick (before sanding!) and the sun shows how thin it is!!
I connected the tops of all frames with two more sets of planks - looks OK and strong.

 

Plan is to use filler, epoxy and glasfabric for strengthening - not sure yet of the order!

 

[FreekS]

I’ve filled some of the gaps with small pieces of wood and a bit of  “liquid wood”.

 

then applied an epoxy layer with a layer of 80g/m2 glass fabric. This was followed by another two layers of epoxy and one inside

the wood filled did discolour a bit with the epoxy, but I think I will leave the hull as it is instead of painting it.

 

I installed a small brushless motor, a couplet and the axle connected to a 40 mm diameter brass prop.

rudder is made from two sheets of hardwood glued together and shaped with file and sandpaper. 
I’ll need to make two small holes in the hull to drive the rudder from a small servo. 

that will be the time for a wet test to see how much current the motor draws, how much ballast to add and if the boat is watertight…

 

 

[FreekS]

Boat has been ballasted with about 1 kg lead plates - glued with epoxy. Motor mount and rudder are functional.

I made the boat 3cm smaller than it’s static predecessor - to allow some room for the rudder. 
after planking the foredeck and aft deck I could test where to put the mounts to hang it in the Davit. The not has 5mm rim in either side but swings out nicely.

In place of the hooks in the decks will come two electromagnets that can each lift 2.5kg and consume 250mV at 6V (visible in foreground).

 

 

[FreekS]

Progress on the lifeboat continues. The electromagnets are installed under the decks - they can unfortunately not be covered with thin veneer as this reduces their force dramatically.

I did add some hardwood along the sides and used veneer on the decks. Cracks were finished with epoxy containing some hardwood sawdust. 
 

inside the boat I used some lighter hardwood for the floor “racks” and the benches. Navigation lights from some brass tubing and these are always on while the white top light can be switched.

the magnets are rated for 2,5kg each (under ideal conditions) at 6V. I’m however driving them via a relais at 10v (3S LiFePo). They do get warm and I need to ensure they are not on too long. So I installed a blue LED in the dashboard to signify when the magnets are powered and the boat can be lifted by the davit. Here the boat is connected to the davit in its case.

 

and the magnets release when they are switched off.

boat is ready for first test tonight - then some more details can be added and I can start to think how to control the davit raising and lowering the boat from the transmitter - without losing sight of the fact that this davit design was manually operated and not powered.

 

[FreekS]

sails well - steering ok, there was about 100ml water in the boat - so I’m doing some more epoxy treatment. Needs a crew though!

[Mirabell61]

excellelant work Freeks,

that looks really nice, also together with the davits

 

Nils

[Bob Cleek]

On 4/9/2023 at 5:15 AM, FreekS said:

there was about 100ml water in the boat - so I’m doing some more epoxy treatment.

Are you sure that water isn't coming in through your propeller shaft bearing?

[robert952]

Fantastic model!  Nicely displayed. 

[Reggiemon]

Looks great on the water!

Display is very neat and adds a lot character to the model.

[FreekS]

On 6/3/2023 at 8:26 PM, Bob Cleek said:

Are you sure that water isn't coming in through your propeller shaft bearing?

The propshaft has a proven simmerring seal. There is no evidence of a leak there. I do expect some leakage where the lines to the rudder go through the hull, especially with motor in reverse. But some grease keeps it out pretty well.

 

thanks for all the likes, I’m starting to think of the automation of the Davit now….!