Black Pearl II Hydro - 2020

[ray schrauwen]

Lol... I can tap the CF but not as nice as aluminum. I'll just use my nuts :)

[lohring]

Consider that the latest motors in P limited hydro are RATED at 3,000 watts. That's around 4 hp. The most outrageous power claims for 7.5 cc nitro engines are less than that. The NAMBA SAW record for a sport 40 is 81 mph set in 2001. The two lap record for sport 40 is 51 seconds. The P limited SAW record is 80 mph set two years ago. The two lap record is 46 seconds. The turn fin loads should be similar.

My sport 40 is 36" long. The P length limit is 34" Maybe it's time to rethink this to avoid running fast, hard to control little boats.

Lohring Miller

[ray schrauwen]

That's partly why I'm running my 34" Pearl in Limited class so that it stays completely planted.

[ray schrauwen]

What prop can I start with on this 34" hull, Huff Leopard 3674 rewind chopped 2300kv, Castle XL2 converted esc, 6500Mah or more...?

1814?

[lohring]

I ran an ABC 1717-19-38 on my outrigger with a motor with similar KV to yours. I'll be running a TenShock with a 2680 KV in the Black Pearl so that prop may be a little big. I can fit two 5000 mah 4S batteries in parallel in it with a Castle MAMBA Monster X ESC. I'll talk to Brian Buaas to see what he thinks.

Lohring Miller

[Reesor@work]

That's partly why I'm running my 34" Pearl in Limited class so that it stays completely planted.

Trust me - you can and will blow that hull off in P Limited. That's huge Kv in that hull for P Limited. I'd start 'small' with props and work your way up - each iteration and prop type will require some trimming. Terry would be the guy to ask regarding a starting point with that Kv. His Pearls are glued to the water and run obscenely fast. I can't believe the props the Michigan guys run in P Limited racing. Lohring is correct - these little motors generate crazy power.

[TRUCKPULL]

Consider that the latest motors in P limited hydro are RATED at 3,000 watts. That's around 4 hp. The most outrageous power claims for 7.5 cc nitro engines are less than that. The NAMBA SAW record for a sport 40 is 81 mph set in 2001. The two lap record for sport 40 is 51 seconds. The P limited SAW record is 80 mph set two years ago. The two lap record is 46 seconds. The turn fin loads should be similar.

My sport 40 is 36" long. The P length limit is 34" Maybe it's time to rethink this to avoid running fast, hard to control little boats.

Lohring Miller

3000 W = over 4 HP

Larry

[lohring]

3000 W = over 4 HP

Larry

OK it's 4.023066267 hp(I) or 4.078864852 hp(M)

Sounds like 4 hp is pretty close.

Lohring Miller

[ray schrauwen]

Trust me - you can and will blow that hull off in P Limited. That's huge Kv in that hull for P Limited. I'd start 'small' with props and work your way up - each iteration and prop type will require some trimming. Terry would be the guy to ask regarding a starting point with that Kv. His Pearls are glued to the water and run obscenely fast. I can't believe the props the Michigan guys run in P Limited racing. Lohring is correct - these little motors generate crazy power.

Thanks Steve. I hope you're doing well.

[ray schrauwen]

I ran an ABC 1717-19-38 on my outrigger with a motor with similar KV to yours. I'll be running a TenShock with a 2680 KV in the Black Pearl so that prop may be a little big. I can fit two 5000 mah 4S batteries in parallel in it with a Castle MAMBA Monster X ESC. I'll talk to Brian Buaas to see what he thinks.

Lohring Miller

Thanks Lohring!

[T.S.Davis]

Terry would be the guy to ask regarding a starting point with that Kv. His Pearls are glued to the water and run obscenely fast.

My Pearl most certainly is not glued to the water. haha.

I'm super hesitant to recommend props without seeing a boat run myself. If I recommend what I really think will work and it bakes a motor........well that sucks.

Best to start small Ray. I think Don runs 17 series props on that motor. I would start around 1814-17-45 maybe. Do the heat check deal every 2 or 3 laps. Remember too that you may/might/maybe need to make strut adjustments for diameter and even rake. An 1814-17-45 vs an 1814-19-38 might need an adjustment. Tiny tiny adjustments are the difference between flight and fast on these. Like .5mm at a time. This is true of all the Pearls in my experience.

[ray schrauwen]

Thanks. I have a 1615 I can try first and some proboat 1716 SS props.

[T.S.Davis]

The 16 likely wont plane.

[ray schrauwen]

LOL... thx again.

[lohring]

Brian thinks an ABC 1715 is good for my Black Pearl with the TenShock motor. We'll see.

Lohring Miller

[TRUCKPULL]

Problem with tape sticking.
I did an epoxy finish on my Pearl.
Epoxy thinned with alcohol, two coats.
I am now having trouble with the tape not wanting to stick.
Do I need to wet sand and put a light coat of clear on it?

Larry

[RandyatBBY]

Problem with tape sticking.
I did an epoxy finish on my Pearl.
Epoxy thinned with alcohol, two coats.
I am now having trouble with the tape not wanting to stick.
Do I need to wet sand and put a light coat of clear on it?

Larry

In the aera that you want to tape, take a light 400grt. wet and dry sand paper to the tape aera. Also a pad inside the sand paper wrap will help to take off high spots. It will stick better and solve the problem. I use 220 grt. and 320 before 400. do not put on as much pressure on the rougher grt. I put up with the sand mark s for better stick. If you do not like the sand look go to finer grt's and buff.

[TRUCKPULL]

Thank you
Randy

I will give that a try.

Larry

[lohring]

I ran my Black Pearl with Brian's 1715 prop. It ran really well until I ran up the rooster tail of the boat I was overtaking. The impact broke the steering servo horn and cracked the transom to bottom joint. It's time to get really serious about reinforcing all the bottom joints.

Lohring Miller

[jaike5]

Did you have any separation from the sides and the bottom pan, from the transom forward ?

[lohring]

Yes, along the rudder side. I opened the bottom joint along the transom and up the rudder side, added epoxy, and clamped shut. I added epoxy fillets to all the interior bottom joints with fiberglass over the transom to bottom joint. We'll see how that holds up.

Lohring Miller

[T.S.Davis]

I reinforce the b'geezus out of the transom. At the corners where the sides meet the trans I place a blocks of oak. Like 1/2" x 1/2" squares. Gives the bottom more to cling to and adds joint strength. Then I back the entire center section with aluminum plate that gets drilled and tapped for hardware later. No nuts to get to ever. This way you can close the transom right off from the world if you want. Then right in the center of the boat I place a wedge (think door stop LOL) against the trans and to the bottom. The transom can't flex much. Less flex makes for less epoxy stresses.

I'll shred a rudder before the trans comes apart. Clearly I'm still scarred from previous failures..... I've had every kind of hydro come apart at the trans. Pi$$es me off. Break away rudders can only do so much.

I'll try to get a pic for you guys.

[T.S.Davis]

Larry, did you use a finishing epoxy? Finishing epoxy has a wax in it. 207 might have it.

[TRUCKPULL]

Larry, did you use a finishing epoxy? Finishing epoxy has a wax in it. 207 might have it.

I used WS 205 & 206 Hardener, with 50 % alcohol.

Larry

[jaike5]

Clearly I have to add more support to the transom before I have the same thing happen.

[ray schrauwen]

It's in the instructions

[ray schrauwen]

I reinforce the b'geezus out of the transom. At the corners where the sides meet the trans I place a blocks of oak. Like 1/2" x 1/2" squares. Gives the bottom more to cling to and adds joint strength. Then I back the entire center section with aluminum plate that gets drilled and tapped for hardware later. No nuts to get to ever. This way you can close the transom right off from the world if you want. Then right in the center of the boat I place a wedge (think door stop LOL) against the trans and to the bottom. The transom can't flex much. Less flex makes for less epoxy stresses.

I'll shred a rudder before the trans comes apart. Clearly I'm still scarred from previous failures..... I've had every kind of hydro come apart at the trans. Pi$$es me off. Break away rudders can only do so much.

I'll try to get a pic for you guys.

Break away rudders need to be tight enough to stop the rudder from moving while running. The faster these get pushed the more stress a rudder hit creates.

Do you even use a brass screw anymore? I find I need to tighten that screw to a point it snaps so on some boats I switched it out for SS bolts.

[jaike5]

Thanks tips !! I'm looking for more beef than the instructions. Life experience is what I Look for. Like Terry's idea of putting in blocks in the corners , wedge at the center line for example. Hope those pics are coming !!

[T.S.Davis]

Do you even use a brass screw anymore?

I crank the top screw like it owes me money and then tighten the brass the best I can. That breakaway isn't just for my protection. I really think that if I locked it in and hit someone I would just cut them in half. My boat would survive but the carnage of an error........yuck. I hate totaling peoples gear.

Jay, are you still running the narrow version? I used to call it the Stealth. That boat is so narrow the transom may never break.

[jaike5]

Hi Terry, I have two of the latest P versions and a early limited version. can't believe I have so many hydros !! think I have the build bug.
I may have to build more this coming winter ! Terry do you build up the spec version as well ?