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Aug 31, 2019, 04:41 PM
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your deadrise looks to be approx 45 degrees in pic. thats very deep which means a very unstable rocky boat. keep all electronics etc in the centre and down low.
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Aug 31, 2019, 10:15 PM
Just Plane Nutts
AirDOGGe's Avatar
Stick with inrunners to help control roll with that steep V-hull. I recommend 3S power and a 2845 3000KV with water jacket. A 30A ESC would do, but I'd go 40A to 60A for more headroom if you seek more speed later and may fit in more motor. Or if it proves too much for the hull, you can swap in a 2S battery for the 3S pack with no mods needed.

This 3100KV with sealed bell ends may be just the ticket: https://www.offshoreelectrics.com/pr...tors+%26+Wires



TIP: TOO much rudder thar!

If that is a 4" tall model ( or 90mm to 95mm), then look for a 3" or 70mm-75mm tall unit for your hull size. If it's the 75mm version then fine, but mount the rudder's strut higher up, as high on the transom as you can. You don't want that much rudder in the water even up on plane.

Compare yours with the 75mm unit on my similar sized 44cm boat ... a little more than half of mine is ABOVE the keel, the lowest point:







Quote:
Originally Posted by crapshooter
your deadrise looks to be approx 45 degrees in pic. thats very deep which means a very unstable rocky boat. keep all electronics etc in the centre and down low.
As I measure, it's 33 degrees from horizontal... see pic below:
Last edited by AirDOGGe; Aug 31, 2019 at 10:51 PM.
Sep 01, 2019, 12:54 AM
Registered User
Jansvast's Avatar
Thread OP
Yeah the deadrise is about 35°, keep in mind i designed it when i was 12. I will mount the rudder higher up and a 2800 - 3000kv 2848 will do just fine i guess The rudder is 75 mm, and i thought more is better because in a left turn it would get out if water (too much deadrise again), but i dont know much about boats. What would happen if the rudder would be too deep?

Regards, Jan
Last edited by Jansvast; Sep 01, 2019 at 02:05 AM.
Sep 01, 2019, 04:33 AM
Registered User
Jansvast's Avatar
Thread OP
After a LOT of sanding, im ready to seal the hull with a strip of fiberglass on the outside, when it hardens im gonna cut out the canopy and add one more strip from the inside I added a drop of super glue on the bow and transom, so the parts cannot move.

I also made a new pair if adjustsble turn fins, the previous were crap...

I found a good 2845 2800kv inrunner on banggood, so i will propably use that
Last edited by Jansvast; Sep 01, 2019 at 05:04 AM.
Sep 01, 2019, 04:14 PM
Just Plane Nutts
AirDOGGe's Avatar
Too deep = extra drag and may hold the bow down at speed (if any).

Like the new turn fins...Much better.


If this boat works out, I bet the smile of a 12-year-old will appear on your face...
Latest blog entry: My You-Tube channel
Sep 02, 2019, 12:22 PM
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Jansvast's Avatar
Thread OP
She is in one piece! I fused the halves together with a fiberglass strip. Then i cut out the hatch and sealed it with some polyester resin from the inside too, so she is 100% watertight (proven in the tub).

Tomorrow i will sand the excess off and apply a thin layer od resin around it, then sand again so it looks nice I will also make an adjustsble motor mount from aluminium sheet.

What would be a good way of adding strakes to the hull, please?

The smile is rising allready...

Edit: just finished sanding with 400 grit water sandpaper and does she look awesome!
Last edited by Jansvast; Sep 02, 2019 at 01:03 PM. Reason: Stupid autocorrect :(
Sep 02, 2019, 02:32 PM
Boaters are nice people.
Hi Jan,

I attached a picture of two hulls showing the position of the strakes.
Note that there is a triangular section there there are no strakes.
On these hull with a lower deadrise, that allows the hull to turn easier and prevents the hull from rising too far out of the water.
Something you should keep in mind; you don't want your hull to rise to high, as it'll fall onto one side...

I would try triangular strips (wood) as strakes, cover in epoxy resin.

Regards, Jan
Sep 02, 2019, 02:47 PM
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Jansvast's Avatar
Thread OP
Thanks! I will run the boat without them first, and then, if i will not be satisfied, i will make them out if balsa How do you like the (almost) finished hull? Excuese the deadrise please.
Sep 02, 2019, 04:46 PM
Just Plane Nutts
AirDOGGe's Avatar
With your steep hull and turn fins (the latter uncommon on jet boats) you may not need strakes. Good call to test as-is first for a reference point to work from with this one-of-a-kind hull.

Use spruce or similar hardwoods for the strakes if you DO go there. Balsa is much too soft and would deform quickly.
Latest blog entry: My You-Tube channel
Sep 03, 2019, 02:31 AM
Registered User
Jansvast's Avatar
Thread OP
Electronics: 2800kv racestar 2845 with a watercooling jacket, flycolor 70a esc with program card.
Sep 03, 2019, 02:49 AM
Boaters are nice people.
Hi Jan,

The motor is fine, the ESC may be on the bulky side, but you'll have reserve for a future project.

A request to make our life easier: don't use screenshots, but post links to the items you're talking about, this saves us the time to search for them...

Regards, Jan.
Sep 03, 2019, 04:00 AM
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Jansvast's Avatar
Thread OP
The esc allows me to try 4s power, and thats very tempting to me What size of prop would you suggest to run on 3s, im a total noob at this... Maybe i will go for 3100kv.

Regards, Jan
Esc:
https://m.aliexpress.com/item/329557...m.32955728818&
Motor:
https://m.aliexpress.com/item/328136...m.32813604493&
Program card:
https://m.aliexpress.com/item/327154...m.32715471402&
Cooling:
https://m.aliexpress.com/item/326269...m.32626912160&
Last edited by Jansvast; Sep 03, 2019 at 04:13 AM.
Sep 03, 2019, 03:09 PM
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Jansvast's Avatar
Thread OP
Today i drilled the holes for the turn fins and trim tabs. I still need to make a silicone seal for them tho, because they leak a LOT.

I tested the boat in the tub with the hardware installed, a 3s 2200 lipo, an old 390 motor and a metal utility knife inside, and she floats very well

I have a question to airdogge: how hight to mount the rudder? I feel like as high on the transom as possible is a bit too much, so here i send 3 pictures with 3 different mounting heights. Which is best?

Thank you, Jan
Sep 03, 2019, 03:47 PM
Registered User
I have a few 17" long mono's & the rudder blade hangs 40mm below the keel & work well. You need the right amount of rudder in the water so that the water pick up is deep enough to pick up water & also there is enough rudder in the water when the boat heels over in a left hand turn where less rudder is in the water to still steer the boat. You also don't want the rudder to deep so as to cause to much drag.
Sep 03, 2019, 05:47 PM
Just Plane Nutts
AirDOGGe's Avatar
Mount it as high as you feel comfortable with. Shoot for around half below/half above the lowest point of the hull if possible
Latest blog entry: My You-Tube channel


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