would a 60 to 70mm propellor be okay on a boat this size

this is my new build of a 60inch fire tender,bought plans from a ebay member in canada who resized them to 60 inch very large boat,don't know what size motor or prop to install so if anyone can help please advise me. would a 60 to 70mm propellor be okay on a boat this size? I will post more pics as I progress with the build. this boat is now in the build blog section with more pics of build

bought this 50inch hull off ebay and thought I would try a make a boat just with my own idears and this is how it turned out,powered by a 720bb motor,12inch propshaft and a 60mm 3 blade brass propellor.all built from odd bits of wood in my shed. installed wood in bottom and then filled with a two part epoxy resin

My own Dusseldorf,powered by origninal robbe navy direckts as these give more than sufficient power to propel the boat at a reasonable speed, all fire monitors operate to fire water and rotate, nav lights, radar, engine sound and fog horn.

This boat was scratch built from Harold Underhill plans, available still from Brown,Son and Ferguson. The hull was mahogany on 6mm ply frames. The engine was a Caton from Maxwell Hemmens supplied bya gas-fired Cheddar Puffin boiler. The propeller was a two inch four bladed brass job from Rivabo I think. The displacement of the boat is 25lb- a bit of a lump to carry to the water but it does work well once in the water. She has now been converted to electric using a MFA geared 540 type motor witha 7.5ah lead acid gel cell. Looking again at this video I begin to wish I had left it as steam but there is something to be said for 'switch on and go'.
I started building the boat in the mid nineties and it has now had a repaint- it always been a favourite. This video was taken in the early noughties at Crealy in Exeter.

This model is a British "Hunt" Class destroyer.

It is a Sirmar limited edition (100) semI kit at 1/48 scale and some 6 feet in length. When he bought the model it was already constructed, but as a static model. So out came the jigsaw, Manual NOT powered.

The deck around the aft gun turret was cut to allow a good inspection of the inside of the hull. He tried to remove the bridge superstructure but this would have meant destroying it to remove. Out came the jigsaw again and cut an access hatch in the main deck.

The steering servo was fitted and attached ( by keyhole surgery ) and 2 x MFA 800 motors were fitted. Scale Prop Shop Props were fitted and the radio gear just jury rigged for her first trial. She was roughly ballasted with 2 x 12volt 7Ah batteries and she was ready for her first trials.

She sailed well with no water ingress to the hull, so the radio gear was installed properly with individual speed controllers to each motor. The results are as seen here.

John called this model "Nancy Dancer". it started of with plans from 'Nexus Plans Service' for Vic Smeed's 'Vivacity'. John used the hull only plans and created everything else himself. it ended up LOA 49" with a beam of 17". With the 12VDC battery the weight came to 23 1/2#.

Because of his basic 'Sedan Cruiser' he designed all the mechanicals and electricals beneath the main cabin floor, including the battery. There was quite a bit of detail put into the main cabin - unfortunately not shown in the photos - including a galley, eating area, furniture and the helmsman's station. The scale is 1" = 1ft.

This hull is plank on frame using 1/8" pine planks. Below the waterline there's epoxy & glass and above there is just epoxy. All the brightwork, cabin housing & decks is natural Cherry with a clear urethane finish.

The power is a Dumas 12VDC motor with a mechanical speed control. The bottom photo shows that he added a 2:1 gearbox to the motor and ran it in reverse to increase the prop RPMs. He also included a constant running fan to cool the motor due to the confinement of the space.

The single propellor is 2" - 2 pitch - 3 bladed bronze. As on all his models he used a 2 channel JR XR2 75 mhz.