If looking for performance, lose weight first*. If the prop is somewhere near, having less to shove will make it all go faster. Changing the prop has at least a 50-50 chance of actually making matters worse.

*Colin Chapman on creating performance – "Add more lightness"

Now then Q Well made videos . and nice looking models but pray tell me why more speed for your models.

They are after all working boats not designed for speed

HOW did you get the video to post on the forum please Thanks Michael

Hi Q Thanks for that ,hope to use it in the near future Michael

Q. Do not be put off by all this talk of "why". I say "why not" !! (as already stated)

A full width trim tab (shelf) at the back would likely assist in the performance stakes by stopping the rear sinking so much, although I do see that the back of the boats are square rather than rounded, which helps.

Trim tabs shift the effective centre of gravity forward a bit by lengthening the hull and are also useful in stopping cavitation, if full width.

yes, 5 blade props are the business.

Ashley

Q. What couplings are you using…you may need to use solid ball/socket ones for this sort of torque.

Prop should NEVER come loose as the thread of the shaft should be screwing INTO the prop under normal rotation and just get tighter rather than looser???

Ashley

HI Q

If your prop is comming loose try a lock nut as well as Loctite/ nut locking fluid, make sure the threads are cleaned with an alcohol such as meths, before putting thread lock on both the shaft and the locknut.

The U/J could be changed for the type the I/C racing boats use, Huco type couplings are sometimes out of balance and it looks like you have a double U/J that makes it even more out of balance.

Mark

Q. Well done for updating us!!

The question of efficiency is a bit complicated. It is horses for courses really. some configurations of prop are more efficient FOR THEIR INTEDED USE than others. One size does not fit all.

​Generally speaking for a model boat prop the more blades the greated overall prop area (for the same size) and so the more power will be needed to turn it. This will give a larger power consumption in amps.

Multi blade props are best run large and slow (sorry, generalisation).

​I have had good results from X pitch 2-blade props being run relatively slowly. It may be that an X60 or 65 if you can get such a beast may be a bit more efficient for what you want (a bit of oomph). BUT who knows?? others will have different opinions.

Ashley

Bigger props, turning at the same rate, will shift more water than smaller ones, but will only move it the same distance in the same time. No more top speed, but better acceleration. The improved acceleration is paid for by increased power consumption during said acceleration. Putting the same power into a small prop will, if the motor can handle it, cause the prop to spin faster. This results in a longer column of water moving faster, which causes the boat to move faster but with less acceleration.

The main benefit of a trim tab at the bottom of the transom is that once the speed has increased enough, the water flow around the stern is broken and drag is suddenly reduced. Even a square edge might not be as square as thought, allowing the water to flow round the corner and grip the transom. The plate of the tab prevents this as well as giving the stern a bit of extra lift.