HK Smash Shark P1

I have just sourced a HK Smash Shark and over the coming summer will do some modifications. As the hull is notorious for chine walking I intend raising the stinger mounting about 3 mm to settle the deep vee in the water. Trimtabs will be fitted and with the raised stinger mounting I assume the trimtabs would be similarly mounted a little higher to minimise drag.

Power will come from a Leopard Hobby 4074 2200kv running 4s power with a Turnigy T3 180 amp ESC.

Ideally I should strip the interior and apply a CF inlay, but after reading a little archival material, I will attach carbon fibre rods internally, covering with 50mm fibreglass tape. The troublesome HK motor mounts and battery mount will also receive a little reinforcement as detailed in the archival material. The transom inner face will also receive a fibreglass overlay.

I have sourced small trimtabs as the Smash Shark is not that wide in the transom. Also, being a little anal when it comes to sufficient water cooling flow, I have sourced a Genesis upgrade rudder with dual outlets and four pickup holes and will adapt this to the stock rudder mount.

A one-piece 3/16" flexshaft has been purchased and a Speedmaster rotating bush will be sourced to finish off the drive. Eventually a 440/3 prop will be fitted, however, for testing I may use the detongued, balanced and sharpened 442 two blade that I have or maybe a 440 two blade.

The boat just arrived in the post this morning and first impression is one of relief. Unlike the recently arrived Apparition, this one looks perfect. Impressive is the hull thickness. The hull bottom and sides are quite thick with no flexing at all.

The Genesis upgrade rudder will fit perfectly. I just need to enlargen the top mount hole on the stock mount bracket to take an M4 bolt and the lower M3 shear bolt.

Old school.
From what I remember when one of our club members was running one of these, the best thing he did for handling was install a longer rudder. The original was way too short. It was mounted high up on the transom which left very little in the water. It certainly got rid of the chine walk. I trust the genesis rudder is longer than the original?
You may not need to raise the driveline if you try a longer rudder first.
The boat loves a de tongued 440/3 blade prop with that size & kv motor. I think he also ran an M445 prop with great success.

The Genesis upgraded rudder is not only longer but wider as well. I have completely dismantled the hull for some reinforcing although am mightily impressed with the stock body. I want to reinforce the transom so have stripped it of components. As the stock stinger has vertical adjustment slots, I have opened out the stuffing tube hole in the transom to take advantage of the possible vertical adjustment. Of cause this will be adequately sealed. I will also address the stuffing tube entry into the stinger tube and modify the tube to take a rotating bush.

A three bladed prop is on the to do list. Many thanks for your guidance.

As suggested in archival material by several members of this site, I have reinforced the stock hull by firstly bonding carbon fibre rod to the motor mounts as these are notorious for separating from the hull and secondly, longitudinal carbon fibre rod is bonded along the hull and then laminated with two layers of fibreglass cloth. The inner face of the transom also received a layer of carbon fibre and then a layer of glass cloth.

post some vids when you get it running. I have two one stock and the other just the hull. So I'd like to see how yours run with said power system and mods. . .I was thinking of LEO4082 or TP4050 or TP4060. . .but 4074 sounds more reasonable than my overkill ideas. I was going to make it bulletproof with cf inlay and see how far I can go with it. .lol...I love the looks of this boat that's why I have two.

Yes, the boat is quite attractive, looking very much like the prototype P1 "Cigarette Smash Poker" from 2009. My first thoughts were to Dremel out the motor mount and battery tray to do a CF inlay, however, the stock hull is impressibly strong, so this is why I went for the CF rods.

I do not think that the boat really needs a great deal of power and from online reports gets a little tricky above 50 mph with excessive chine walking. I have attached a larger rudder plus ordered small trimtabs to fit. I will replace the turnfins. I may raise the stinger a few millimetres and if too 'wet' will lower it. There seems a fair bit of room to play with battery placement. There are a few videos on You-tube showing very badly set up boats so hopefully mine will not fall in that category.

If I can get a stable boat over 50 mph on 4s then I will be pleased.

It is now up to running stage once the shaft is greased. Shown are the carbon rod reinforcing with the glass overlay. The stock turnfins are fitted and these will be either modified to a traditional dagger shape or purchased. These have a 3mm mount whereas the dagger fins that I have are 4mm.

I am awaiting trimtabs. I must say that I am most impressed with the construction of the hull and hopefully with the further reinforcing carried out it should prove to be robust. Due the oversize Genesis upgrade rudder I found on left turns that the rudder was closer than I liked to the propellor so fitted a stop bolt to the rudder support arm to limit full left travel. The prop is a detongued, balanced and sharpened 42 mm two-blade. Eventually I will source a 440/3 propellor.

Would love to see pics of the work done

Alas, no build photographs. Basically the following has been done -

Hull and motor mount reinforcement
Genesis upgrade rudder with dual water pickup
Leopard Hobby 4074 2200kv brushless motor
Turnigy 180 amp ESC
One piece flexshaft
Detongued, backcut TFL 442 propellor
Still to do, am awaiting trimtabs to fit

looks like a nice mono. don,t forget to clip up the water lines to nipples plus i bet you will find that 442 modded prop will be too small for the 4074 power. yes 440 x 3 blade stock.

A 440/3 is on the shopping list. When I first sighted the boat on the HK site I was only mildly enthused, but after working on it it has grown on me. I am not interested in developing the boat further other than the prop upgrade. I am hoping that performance on 4s will be reasonably impressive.

have you install the trim tab yet any pics??

Trim tabs fitted. Due the restricted space I chose the small version. A little fiddly to fit the starboard side as the rudder assembly limited access.

This is the type I used (not from this seller)

https://www.ebay.com.au/itm/RC-282-2....c100005.m1851

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Originally Posted by rol243

...................... plus i bet you will find that 442 modded prop will be too small for the 4074 power. yes 440 x 3 blade stock.

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While awaiting the arrival of the stock X440/3 prop I tried the boat with the detongued modified 442 and the result was a dismal failure. Because I assume of the detongueing the prop has no torque from a standstill and the boat struggled to get on a plane.

Where is the balance point on the boat with the setup you have shown in post #8? It should be at about 28-30% of the length of the boat, forward of the transom, not including the overhang.
The battery looks too far forward to me. I think we ran that type of boat with the battery close to the motor & the ESC beside the motor on the left.
That m442 should get that boat up on the plane if the cog is right.

Im having the same issue with my hk outerlimit.

The balance point is at approximately 35%. The battery is in the location as set by HK. I will relocate the ESC and bring the battery aft. I believe the TFL detongued prop that I used has not enough blade area to get the boat moving.

Why didn't you mount the trim tabs flush with the bottom of the hull?

With the ESC to the left side aft and the battery moved aft to the motor, it shifted the C of G approximately 1.25 inches aft making it still around 33%.

As regards the trimtabs, sitting them flush would have positioned them under the stinger shaft location on the transom placing them always in the water.

Ummmm..your hull will be keeping them out of the water.

Trimtabs should be about 1-2mm above the bottom
But i doubt he will need the with the cg so far forward

I have not been able to test yet, however, a search on Google returned a result whereby if in initial setup the throttle reversing switch on the transmitter is in the "REV" position and the motor is set to turn in the correct rotation relative to the prop then full throttle application on the transmitter will only see approximately 50% throttle at the ESC. On my transmitter the writing is so small that 20/20 vision is needed to see the switch position. My transmitter had the switch in the "REV" position. I have corrected the situation with the switch in the normal position, set throttle range on the ESC and motor rotation normal.

To sum up, apart from correcting the situation above, I have shifted the C of G slightly aft (1.25") , lowered the stinger to lowest possible position, fitted a rotating bushing (to minimise friction in the drive) and fitted a 440/3 prop. I know shifting the C of G did not get the boat on plane so hoping that any of the other corrections will help when I finally get to test the boat.

I finally was able to test the boat after doing the above modifications. The boat now has a very good turn of speed however, under power the hull porpoises. When power is applied the hull accelerates hard but then with speed increase it becomes decidedly unstable with the bow rising and falling. The hull completely leaves the water as the bow rises and then the boat settles back into the water and repeats the process (stinger strut was adjusted in a neutral position).

Unfortunately, I was unable to retest the boat after moving the battery forward approximately an inch (almost to original stock position) and adjusting the stinger strut with a negative adjustment to hopefully keep the bow down under acceleration. The hull seemed fine under right hand turns but seemed to chinewalk slightly on left turns. As the boat passed over ripples in the water from previous passes it did seem to induce a little chine walking but otherwise not evident.

After ten minutes runtime (4s 5000 mah 45C) only the additional factory caps on the ESC were warm. The motor, battery and ESC were all almost cold.

sounds like the trimming is nearly there. its good if you can leave the prop set parallel with zero neg or positive and just correct the trim via battery placement. good run time too, check voltage per cell to make sure all is safe.

Each cell read 3.5 volts after the run (ran until LVC). I was amazed at the change in performance. Previously it could only raise the bow and push through the water like a displacement hull. Now it flies, not as quick as my son's cat but a joy to watch.

I have a Grim Racer 44 1.5 2-blade to try, but as my son starts next Monday with the Queensland Ambulance Service as a paramedic, today was the last day we both could be on the water. I may have to join a club??????????