Bob,
So is the prop shaft not only shorter, but mounted further forward, or is it just a shorter length of shaft below the hull, placing the prop and therefore thrust more centrally along the waterline length?
If the prop and therefore thrust/propulsion was nearer the stern, then it wouldn't try to lift the whole hull up as well as push forward and would need the increase in speed along the hull, to raise onto the plane. Yes this would mean taking longer/more throttle/increased speed before coming up onto the plane, but would it alter the characteristics of the hull, especially when passing over a wake, I don't know.
Or, are the current characteristics caused by reduced weight compared to how it would have been with the intended power system(i.c or especially electric).
What do you reckon?
Will
The prop shaft is shorter that shown on the LesRo kit plan and the rudder is further forward too - very similar to the layout used by Vic Smeed on his Remora design. The prop shaft is not very far forward inside the engine bay, the outer shaft only just passes through the "firewall" bulkhead to give as little unsupported overhang as possible.
If you scroll back to the pictures (above) of the interior of Rapier1 you will see that the brushless motor almost looks lost in the engine bay, and when compared to most of this space being taken up with the intended 40 - 61 size glow motor there would have been a lot more weight in this area and most of it would have been further forwards.
The wheelhouse cabin is where the fuel tank would have been positioned if the boat was ic powered. I fit two lightweight 2 cell LiPo cells here. One is connected to power the boat and the other is carried to balance the hull equally either side of the keel centre-line. The ESC and RX are also mounted in this area, but they have no significant weight.
The rear cabin is almost empty as it only has a standard size steering servo along with four button magnets to retain a couple of small tools to use when changing a propeller or an alternative brushless motor if I want to do this when I am lakeside, but none of this adds up to any significant weight.
No ballast is carried in the hull - only the items listed above.
The design of the boat has a longer than average foredeck area and the section inside it (like most other model power boats) is "closed" so there is no access to what would be an ideal place to hide some ballast that could be used to see if this could give a more "nose down" attitude to the boat when it is at speed.
The boat looks good on the water - it is not running with the bows in the air and the stern below the surface - it runs (when at speed) with a very level attitude that is more or less parallel with the waters surface, but only the rear half of the hull is in the water.
The curved "anhedral" shape of the boat and its deck line is unusual and is probably why the boat has the stance of an off-shore racer at speed rather than the more normal "cabin cruiser" shape of hull that has to "plough" its way through the water.
I may try adding some lead to the front of the engine bay to see what the difference would be if more of the hull was in the water when the boat is running at speed. I would be interested to find out if running with more of the hull in the water has any effect on the hulls ability to shrug-off any of the slight "nods" that the hull displays has after crossing a wake or a wave at speed.
As a matter of interest, when the boat is stationary is sits nice and level in the water and show none of the well know Fairey models tendencies to sit with a nose down attitude so maybe a little forward ballast of worth a try?
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Topic: Lesro Rapier - 60's cabin cruiser (Read 43394 times)