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[Stuw]

Nice footage of the Rapiers there! As far as I can make out, neither appear to be sporting strakes. The electric one on the calmer lake looks great once going at speed. It has encouraged me to get Javelin 1 going again.


I have dug out some old photos of my Javelin when she was new which I will try to scan in. I will attach to Javelin thread but they show the boat at speed and also my home made water jacket for the ex RC aircraft IC motor.

[zooma]

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.

What do you reckon?

Will

Sorry I didnt read this bit as well as I might have done Will.

Just to clarify, the prop shaft is still mounted in the same location passing though the same slot in the keel "as per Rapier kit plan".

Part of the prop shaft length shortening is inside the engine bay where it only just protrudes through the firewall bulkhead - bringing the already lighter power plant further back in the hull than its intended (heavier) i.c. engine would have been, so the weight of Rapier1 is quite a bit further back than Les Rowells plan intended it to be - moving the hull balance further rearwards.

The other area where the shaft has been shorted is after it leaves the hull (under-water) making it further away from the stern.  I have also moved the rudder further forwards to make to closer to the propeller, so the underside positions of the prop and rudder are very similar to the positions of the Vic Smeed Remora .

Hope this helps you to understand my "waffle" a little better.

Stay safe,

Bob.

[madwelshman]

No apology needed Bob 


So like I said, the prop being further forward would increase lift more centrally, rather than from nearer to the stern, which with the longer shaft/prop position being closer to the stern, would keep the bow down a bit, due to the thrust being from further aft.
Add into this, the fact that the whole power plant not only being lighter, is more centrally mounted, the bow is going to be lighter and ride higher.
It could be argued that with a more central balance point the boat will handle better at speed.


So really, I guess it all comes down to if you can live with it as is or whether or not you want to go to the with removing and replacing the shaft, moving the rudder(again) and the motor mount too.


If it goes well, handles and turns well, then as long as the porpoising after crossing a wake isn't too bad or for too long, then I'd be tempted to live with it.


You could try altering battery location(if possible), or adding additional ballast in the bow to see what [/size]difference it makes, just to satisfy your curiosity.


Will

[zooma]

No apology needed Bob 


So like I said, the prop being further forward would increase lift more centrally, rather than from nearer to the stern, which with the longer shaft/prop position being closer to the stern, would keep the bow down a bit, due to the thrust being from further aft.
Add into this, the fact that the whole power plant not only being lighter, is more centrally mounted, the bow is going to be lighter and ride higher.
It could be argued that with a more central balance point the boat will handle better at speed.


So really, I guess it all comes down to if you can live with it as is or whether or not you want to go to the with removing and replacing the shaft, moving the rudder(again) and the motor mount too.


If it goes well, handles and turns well, then as long as the porpoising after crossing a wake isn't too bad or for too long, then I'd be tempted to live with it.


You could try altering battery location(if possible), or adding additional ballast in the bow to see whatdifference it makes, just to satisfy your curiosity.


Will

Thanks Will,

I really don't think that the slight "nodding" after it crosses a wake or wave is too concerning - more a point of interest really - but I was wondering if a slightly lower bows position when high speed cruising would reduce this at all?

Your reasoning about having a prop shaft closer to the stern to cause the bows to run lower makes sense and could well be why Rapier1 runs with its bows slightly higher out of the water than those that we have seen on the youtube videos.  The large strakes may also help to give the hull a little extra lift too (perhaps)?

The transom does not sit any lower in the water than the Rapiers we have seen on the videos. If I can run Rapier1 in some choppy water I can make a better comparison between them and Rapier1.

Rearranging the LiPo positions (or just adding a little nose weight) will see if this will encourage the boat to run with a little more hull in the water and note if this takes away any of the boats excellent responsiveness. I could also try running it with just one LiPo in the hull (as Harry suggested) to halve the midships "ballast" weight.

At the moment the "advantages" of having a slightly shorter prop shaft with a more forward position rudder include a very fast and stable turning radius that the boat can achieve at almost all speeds, and maybe it also contributes to the fast rise up onto the plane.

The boat does gets up on the plane every quickly and it is very stable (other than the slight occasional "nod" already mentioned) which is good for a boat that is probably going much faster than it was intended to go.

It will be interesting to observe what differences re-distributing some weight will make as well as seeing what happens when some additional nose weight ballast is added.

Stay safe!

Bob.

[zooma]

Rapier1 was running well on Saturday with an X45 prop. I up-propped it to an X55 on Sunday and it was running just as well - the change of prop made no difference  that was noticeable.

A fellow user of the boating lake arrived on Sunday morning with a large collection of r/c model boats that he progressively worked his way through during the day and he was obviously enjoying himself, but he did no have too much in the way of "hand to eye" co-ordination so his various models were always likely to be taking an irregular path of travel that was not possible to predict.

I had managed to stay clear of his models (including some reasonably fast craft that seemed to have a homing device fitted to them at times) as Rapier1 is reasonably quick and has excellent steering so getting out of the way (although a little "hairy" at times) was safely achieved and I was still able to enjoy my boating.

However - the sight and sound of a Blackjack 29 hurting across the water remind me of just how fast these boats are  -  especially when apparently out of control and darting violently in a multitude of directions every few parts of a second, so I decided cowardice could be a good trait to display and started to return to shore by running close to the edge of the lake to present as small a target as possible and to stay away from as much open water as possible.

Sadly during this dash to safety Rapier1 hit a solid submerged object and few up into the air. I killed the throttle before the boat landed on the edge of the lake and walked around to retrieve it.

I could not see what the boat had hit and I don't normally run this close to the edge so it may be a well known obstacle - but it was a new one to me that ejected Rapier1 clean out of the water at some speed.

When I lifted the boat I could see that the rudder had been bent back into the bottom skin so I unplugged the LiPo and put it in the car so I could check it properly when I get home to see if the gears in the steering servo have been stripped, straighten or replace the rudder shaft, repair the bottom skin, and check to see if there is any other damage that was not apparent at the time.

My first impression was that Rapier1 is a tough old bird that although being well over 50 years old looks to have suffered only minor damage - and if this is the case, this old boat has shrugged-off a violent high speed crash that was brutal enough to throw the boat completely out of the water and live to play another day......hopefully next weekend!   

[madwelshman]

Unfortunate Bob, but she lives to see another pond, that's the main thing.
The damage isn't too extensive, so I'm sure you'll have her back on the water in no time.


Will

[ChrisF]

That's a bummer, though as you say easily fixed.

Given that the rudder hit it the obstacle it must only be just below the surface.

Chris

[zooma]

I gave the boat a quick check over last night and removed the rudder to see that the shaft is bent in two directions but after scraping off the paint and checking around the area of the bend (and the two rivets) I could see no splits in the brass shaft, so I will apply some heat and see if it straightens OK.  If it does I will reduce the size of the blade and re-use it on a smaller model where it will be under less pressure, but I will fit a new rudder to this boat.

The M5 X55 prop has some minor damage to the leading edge of one blade only so I will match the slight change of shape to the other side. The Turnigy 3648-1450 out-runner does not seem to be at all prop-fussy so I will run it again and see if it makes any noticeable difference, but I will order a new replacement propeller.

The bottom skin has not been punctured so that will be easy to sand smooth and repaint where needed, so although the crash looked spectacular as the boat threw itself out of the water to land on the edge of the lake, the actual damage is very slight so with a new rudder and a little bit of time and paint it should be back in action again this weekend.

[Stuw]

Sorry to hear this Bob 


After all the hard work that goes into these builds/restorations it doesn’t take much to potentially undo all the hard work!


Sounds like it’s minor damage?! Wonder what was under the water to get the Rapier airborne?


Could have been a lot worse if you’d been in a collision though!

[tonyH]

Wot, no no claims bonus......

[zooma]

Sorry to hear this Bob 


After all the hard work that goes into these builds/restorations it doesn’t take much to potentially undo all the hard work!


Sounds like it’s minor damage?! Wonder what was under the water to get the Rapier airborne?


Could have been a lot worse if you’d been in a collision though!

Hi Stuw,

You are right!    I may have been a bit unlucky to hit something under-water, but a high speed collision was a real possibility that could have been far worse, so I am still happy that on his occasion cowardice was probably the better part of valour and the damage was only slight and won't take much to fix.

As expected, the Blackjack 29 run time was not too long and it was replaced with another model from the visiting fleet a few minutes later. Luckily, I had my old Vector 80 in the car, so I gave it a couple of runs after putting Rapier1 away and enjoyed the rest of my day!

This old Rapier continues to impress me and I am so pleased that I restored it during the first lock-down as it has given me many hours of fun and pleasure ever since.

Stay safe!

Bob.

[zooma]

That's a bummer, though as you say easily fixed.

Given that the rudder hit it the obstacle it must only be just below the surface.

Chris

Being just below the surface may have been a blessing - if it had been at surface level (and I had not seen it) the damage could have been much worse as the hull would have struck it at speed.

[zooma]

The repair work on Rapier1 is coming along OK, and I have taken the opportunity to change the motor from the fire breathing (but greedy) Turnigy 3648-1450 out-runner for a Surpass 3548-1100KV out-runner.

These are similar sized motors but the Surpass is just a little smaller but should give a "similar" performance.

The motor swap took about 2 minutes as I had already mounted the Surpass onto another 'same sort" water-cooled alloy motor mount to allow for a quick change. 

The Turnigy will be coming with me when I next go to the lake so that I can swap in back just as quickly (I carry the right size Allen key on a pair of small magnets in the rear compartment alongside the steering servo) if the Surpass fails to work as well as I hope it will.

Apart from enjoying a little experimentation, I have wanted to try a Surpass out-runner for some time so this will be my first run with one and I am hoping to see if I can gain a little more than the average 7 minutes run time that I currently get with the Turnigy using 5500Mah 2S cells.

[madwelshman]

Evening Bob, it will be interesting to hear what difference you find between these two motors.

Glad that the repair work is coming along ok. I'm sure she'll be back on the water again in no time.

Will

[tonyH]

Zooma going green? I don't believe it!!!!!!

[zooma]

I also found the large slab of folded lead sheet that was found hidden under the wheelhouse floor of Rapier2 when I first bought it, so I unfolded a small section of it and sliced a couple to lengths up to place infront to the motor position to see if it has any effect on the slight "nose bobbing" that Rapier1 displays after passing over a wake at speed.


This "nose bobbing" is not a major problem but as others have mentioned it could be due to the boat balance being a little light in the nose so I will progressively add strips of lead until it either makes a difference.......or the boat get too heavy to carry 


If I do find an optimum amount of lead that works, I will put a wood screw through the lead to secure it to the keel and if it is to become a permanent feature I will secure it with 'Sticks Like Sh*t" as this can be blended in to look like a finished job.

[tonyH]

No comment...

[zooma]

The bent rudder did straighten-up again OK, but I can see a slight hairline crack next to one of the two rivets and the blade is also slightly loose. so I used a small ball pane hammer to tighten the stretched rivets but I will fit a new rudder until I have time to make a hearth and get some kit together so that I can silver-solder it.

Rapier1 has been running really well with the Extra Large size rudder, but I am going to fit a standard large size rudder this time as it is closer to the shape drawn on the kit plans and see how it goes.

[zooma]

Fitting the new rudder was a simple enough job, but there was a fair bit of "slop" between the rudder shaft and the mounting tube, enough to cause concern and probably enough to encourage water to seep up between the shaft and the tube.

The rudder was one of the commercially available types that come with a black plastic moulded mounting tube and I am guessing that when the boat hit a submerged object and bent the rudder shaft it stretched and elongated the moulded mounting tube too?

I checked the replacement rudder (and the old straightened one) in a new moulded mounting tube and they both fitted well enough and without any excess "play" so the old mounting tube had to be removed and replaced.

The mounting shaft had been installed "a bit too well" to make it an easy exchange as it had been "set" into the keel with Araldite that was used as a seal to protect the plywood keel from any water ingress.  The brass fastening nut unscrewed easily enough but the brass base washer and the mounting tube itself were both "laminated" into the hull.

Sometimes a light tap with a hammer can cause hardened epoxy resin to shatter or crack away, but not in this case, so the tube was drilled-out.

Some damage to the paint on the hull underside was caused as the lower end of the mounting shaft that acts like a bearing for the top surface of the rudder to turn against was also laminated in place and needed to be cut away and took some of the surrounding paint with it, so this was replaced after the new unit had been fitted. The rudder shaft was greased to help it turn smoothly and to prevent water creeping up the mounting tube so the repair is now completed.

Once the steering linkage is straightened and fitted, the Futaba 9304 steering servo can be checked to make sure it still works OK (it turns smoothly enough by hand) and that the new Surpass motor has been wired in the correct orientation, and if it all checks-out OK the boat will be on its way to Southport tomorrow to check everything is OK and watertight.

[zooma]

Rapier1 has had a lot of running this week and everything is working well.
The Surpass motor has given a very much quieter running boat, so the excess noise that I have been trying to kill has sorted itself out with the change of motor.
The boat is not as fast as it was with the Turnigy motor but it is still quite quick and the running time has almost doubled to average well over 11 minutes of flat out running so it has been a very interesting experiment.
The smaller rudder has made no noticeable difference to the Extra Large original, but I will check the steering response again when the more powerful motor is refitted.
The lead weight that was added to the front of the engine bay has also reduced the tendency for the nose to bob after riding over a wake, but like the smaller rudder performance, I am aware that this was seen at a lower speed so I will also check this again when the boat starts to run faster again.
Overall, the testing has all gone very well with no nothing negative to report.

[madwelshman]

Well done Bob, glad to hear that Rapier1 is back on the water and running well, especially with doubled running time, that's a huge bonus, even if it's not quite as quick as it was with the other motor fitted.


Will

[Stuw]

Interesting that the noise has reduced with a different motor! Glad to hear you have had some good run time.


I haven’t had time to devote to boats recently as the garden (veg patch) has needed more attention along with making a skateboard for my son. I shall hopefully get back to tinkering with my boat soon but as it’s summertime maybe not!

[zooma]

A very slight leak in the rear compartment was noticed after several runs with Rapier1, so I will remove the new rudder mounting post and (reluctantly) refit it with a nice coating of Araldite to seal it into the keel.

This should have been done when the new assembly was fitted, but I had hoped that I could get away without doing this as the tube was a very good tight fit (it needed to be screwed into place) and this would have made any future replacements a simple matter of unscrewing this one and fitting the replacement rather than having to drill it out again!

The chances of bending another (smaller) rudder are pretty slim (and drilling the plastic mounting tube out and cleaning it up only took a few minutes)  so I don't suppose it is too much of a problem,  but it does go to show how merciless water is in "seeking out" even the slightest opportunity to creep in through the smallest of cracks or spaces.

When this is done I will re-paint this rear compartment again and grease the rudder shaft again.......just to be sure!

[zooma]

When I was sorting-out the small leak in the rear compartment of Rapier1 (rudder tube) I decided to take a look at the plans to see what was underneath that very long Rapier foredeck.

The front engine bay bulkhead B2 is where the long foredeck starts and it has the front windscreen above it, but the plans showed that the next bulkhead B1 is a full 5" in front, so this leaves quite a large empty void that has never been investigated.

This sealed compartment is not accessible once the boat has been finished so I have never been able to take a look inside to see how well the original build was done and how well the old adhesive is holding up.

A plan is being formed (in my mind) to cut a section out of the deck so I can take a look inside, and maybe make some sort of removable hatch or skylight to allow access at any time.

This would also give the option of adding some glass fibre matting and resin to strengthen this normally unseen section of the hull, and of course it would be a much better place to position any nose weight as I would need less of it to balance the boat !

When I get back home again, I will take a look at this and see what I can come up with that would do the job without looking too ugly or spoiling the lines of this classic model boat.

[Stuw]

Good idea Bob to get a look at this part of the hull. As you know, I cut (hacked?) my way into this area through the bulkhead on my Javelin. I wonder if it would give you enough access to apply resin or glass if you perhaps opened up the bulkhead instead of the deck?


You could then plug it again perhaps with a removable section if necessary?


No more progress on my projects yet due many other things to do with greater priority (such as fill cracks on outside of house  ) and weather is too good to be in the garage. But I have plenty of wood in stock for when I do get on with it!