The full-size vessel has five-blade props, counter-rotating outwards (from the top). The prototype plank-on-frame model had geared 545 motors and so had no problem turning five-blade props. Unfortunately I've seen several grossly-overpowered examples – one even had 2-blade plastic X props! It really depends on what motors and what voltage your model is running. Do you know what type of motors you have and can you say what the voltage of the battery pack(s) is? You must appreciate that Sentinel is what Vosper's designers call a 'short, fat warship' so a model would move at a speed more like a destroyer's than an MTB's.

Dave M

You have to Create an Album first. Go to the Grey toolbar at the very top of the page and click on Albums, then Create an Album and follow it from there. You can load photos which are in JPG format by Browsing for them on your computer's drive. Once you've uploaded and saved them you can add a photo from your album to a posting by clicking on the camera icon above which says Insert Image from Album. It's not that difficult – even I managed it!

My money says the model has two Speed 600 motors, in which case a transplant will be required! 9.6v is quite definitely more than is required.

Dave M

There are 540's and then there are other 540's. Some would be hard-pressed to pull the skin off a rice pudding on 24 volts and others would happily pull your arm off on 6v. They look the same from outside. A 'standard' one is rated at no more than 7.2v, and 40mm x 3-blade props are on the large side. I would hesitate to run any on 9.6v unless I knew more about the motors. Is there a manufacturer's label on them (e.g. MFA, Graupner)?
Rule of thumb for direct drive (brushed motors) is not to use props which are larger in diameter than the motor case.

DM

William. They look like MFA 540, seeing the black label. They are rated to 15v, but are weedy motors.

This is a weight concious model. Brushless would be good, something to give, say 12,000 rpm, at 9.6v for good performance. However will need two speed controllers, so a bit fiddly.

OR…possibly a pair of J.Perkins speed 480 motors and new 30mm or 35mm props. these are rated at 9.6v and a feisty little motors. I would also get some new flexible couplings from Model Boat Bits to suit.

Ashley

Ashley

The Perkins 480 motors on 9.6v will be turning at 22000RPM no load. As J P McEnroe once said, you cannot be serious! With luck you'd just boil the lake away while the model sits in a froth of cavitation – until the bearings burned out. If you're unlucky the wiring would catch fire and destroy the model as well.
Sentinel is NOT a "performance" boat. The full-size spent most of her time in trolling gear or loitering on the waterjet at less than walking pace, tailing suspect yachts which were just over the horizon with her clever-clever electronics. Maximum speed was used only during short-dash intercepts within territorial waters; in transit from one mission to another, or back to Gosport if Chris Pratt, the captain, had promised to buy the drinks……. Top speed is still classified but I can reveal it wasn't much over 30 knots, and the hull is described only as "semi-planing" – whatever that means. For information my original Sentinel had 6mm less freeboard than the kit version and used one pack of six D-sized 9AH NiMH cells for everything. It was rock-solid in turns without working stabilizers.
As the designer of both kits I've always found it puzzling that folk will grossly overpower Sentinel and yet load down Huntsman with SLA batteries until it sails like a narrow-boat. Can anyone enlighten me?

Dave M

Good luck with those.

DM