Delta Force 45MKII - Ambitious first boat build

[zedextreme8177]

Hi everyone! Now that it's close to completion, I would like to share with you my DF45MKII build, which has been slowly progressing over the year.

This is my first build, and so far has involved a pretty steep learning curve with a lot of mistakes made. I'm happy with how it turned out though, and lurking on these forums helps a lot

Parts list:

Hardware
- Speedmaster 4" dual pickup rudder, .187 Mono round-bottom strut, and Large turn fins
- OSE 2.25" medium dual trim tabs
- Aeromarine large-bore water outlets and transom fittings
- Kintec Racing antenna mount, cowl locks and transom boot mount
- Dubro 4-40 steering hardware with ball links, and Kwik-switch

Driveline
- Aeromarine .187 welded flex cable
- Kintec Racing drive dog and collet
- ABC 2314 Prop

Electronics
- TP4070 1Y 1520kv motor
- MGM TMM25035-3 X2-Series ESC
- 4 x Gens Ace 2700mAh 6S 45C batteries in parallel
- Futaba 3PV radio with R203GF receiver


Here's the hull next to the IM31 for reference, and measures approximately 38.5" long:
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[zedextreme8177]

First, I started off with the inlay. This is standard 2x2 twill-weave CF in a single layer, as the hull is already pretty solid as it is. I used Epiglass HT9000 epoxy which cures slightly yellow. Afterwards, I made a mockup of the stringers, which were to be made of CF with 4" spacing,


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[zedextreme8177]

Next, I mocked up the hardware using masking tape and 2-sided tape. Then the holes were drilled and the hardware test fitted.

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[zedextreme8177]

In the meantime, I made a simple boat stand from PVC and insulation

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Painted to match the boat's planned scheme:

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[zedextreme8177]

At this point, I had a general idea of how I wanted to lay everything out within the hull stringers. I drew some 2D CAD parts and sent them to be cut. Nick at CNC Madness did a great job with these components!

Here you can see the stringers, battery tray, servo/rx mount and flood tube caps
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Mocked up inside the hull, I will be using furniture brackets to attach the trays to the stringers
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[zedextreme8177]

The stringers were drilled and the parts mounted together:
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Afterwards, I installed the cowl locks and steering rod. Bent and lined up with the servo from the inside:
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[zedextreme8177]

Here's the motor, and next to the Leopard 4074 in the IM31
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I put the motor in an HRC mount just for the pic, then removed the sticker and installed a 40 x 85mm water jacket
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[zedextreme8177]

After some more CAD drawings, I had some more custom parts made by CNC Madness.
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A few hours with thread taps gave me these, which makes the whole assembly process far easier!
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Did the same for the motor mount, while waiting on a 2.5mm tap for the ESC mount holes:
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[TheShaddix]

Awesome build. I like your motor choice. That water jacket looks really nice too! i'd go with an mbp collet though, not a cheap chinese one that will most likely wobble. One thing I really don't like about this hull is those hatch corners at the back, not sure why they designed it in such a way, it's harder to tape over those. Are you going to fill yours before painting?

[zedextreme8177]

Awesome build. I like your motor choice. That water jacket looks really nice too! i'd go with an mbp collet though, not a cheap chinese one that will most likely wobble. One thing I really don't like about this hull is those hatch corners at the back, not sure why they designed it in such a way, it's harder to tape over those. Are you going to fill yours before painting?

Thank you very much! The jacket is pretty big with good sized inlets, and should provide plenty of flow!

The collet is from Kintec racing, which so far has vibration and wobble-free. However, I might try out an MBP collet as well

As for the hatch, I've filled out the circular gap in the rear, still the corners are kinda tricky to tape over. In fact, I'm considering changing over to a tapeless hatch design with hatch bolts and a neoprene seal around the lip.

[zooma]

Great build. Great engineering. My concern would be the rudder pushrod. I don't think threaded rod is strong enough. And, it has too many bends to withstand the stress of this size and speed of boat.

[martin]

The hatch corners were designed for nitro engine use where hatch fixings were used & taping the hull wasn't used obviously. They never got around to modifying the moulds for electric use.

[zedextreme8177]

Great build. Great engineering. My concern would be the rudder pushrod. I don't think threaded rod is strong enough. And, it has too many bends to withstand the stress of this size and speed of boat.

Thank you very much! Yes, the linkage is something I will keep an eye on during the initial runs. If there are any handling issues, I will come up with a thicker and more solid linkage design.

The hatch corners were designed for nitro engine use where hatch fixings were used & taping the hull wasn't used obviously. They never got around to modifying the moulds for electric use.

True! Apparently, only recently did they even start getting the molds for hatches without an exhaust cutout.

[zedextreme8177]

Here's the motor mounted in the hull.
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Time to fix the stringers to the hull! Some masking tape to mark out the location of the stringers, then initially tacking them with 30-minute epoxy
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Next, I laid in some carbon fiber along the sides. This didn't turn out too nice! However, the stringers are rock-solid now, and for the next build I will use carbon fiber tape to keep things cleaner.
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[zedextreme8177]

Next, I cut and bent the 1/4" stuffing tube with an S-bend. (Possibly a bit too sharp of a bend?)
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Here I used a short piece of 9/32" tubing, this will allow me to remove the stuffing tube should I have to. The end-cap is made of two circles (18mm and 20mm diameter) glued together and drilled. This was then epoxied in place to one end of the flood tube.
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Next, I fixed the flood tube in place. The rear is fixed in place with 2-part epoxy, while the front is supported with a few layers of crushed CF fibers. This turned out much stronger than expected, and the entire boat can be lifted from the flood tube alone. From here, it's a straight shot to the motor collet.
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Paint-job photos coming tomorrow