ePropulsion Pod Drive

[jonbouy]

I'd worry a little about longevity, there are signs of corrosion on my Spirit after only one year use (but to be fair, the same can be said of most outboards).

I sent my Spirit 1.0 back to Nestaway for a replacement part after a year as I ran over a rope - they called me to say that they weren't happy with the paint and some corrosion on the bulb and would be replacing the motor which they promptly did. I've had the replacement for 18 months with no sign of corrosion at all. I think he mentioned to me on the phone that there were some early batches that had the problem so it may be worth enquiring?

I too would not go back to a petrol outboard. My main reason apart from the quiet and lack of smell is that my wife and daughter have no problems jumping in the boat and pressing go - they didn't feel that way about the petrol.

 

[Bull City]

@jonbouy  Thanks for that info. Do you sail in salt water?

What is Nestaway?

 

[chester]

what exactly passes throuth the hull?  three bolts and the wiring harness so 4 holes?  or that compensation wedge?

View attachment 417311

 

[TwoLegged]

@chester, from what I read, the compensation block remains outside the hull, and has to be trimmed to fit the hull contours.

 

[chester]

@chester, from what I read, the compensation block remains outside the hull, and has to be trimmed to fit the hull contours.

right, so then a mounting plate tha spans the chanel and ecceps the bolts on a flat plane should be pretty easy, no?  assumes enough length in the bolts to go through, laminate and the plate.

 

[TwoLegged]

right, so then a mounting plate tha spans the chanel and ecceps the bolts on a flat plane should be pretty easy, no?  assumes enough length in the bolts to go through, laminate and the plate.

Yes, but as Bull pointed out, the plastic riser for the cables sits right in the middle of the drainage channel, so there will be some blockage of the flow to the bilge sump.

 

[chester]

right

 

[Bull City]

@chester, from what I read, the compensation block remains outside the hull, and has to be trimmed to fit the hull contours.

right, so then a mounting plate tha spans the chanel and ecceps the bolts on a flat plane should be pretty easy, no?  assumes enough length in the bolts to go through, laminate and the plate.

Yes, but as Bull pointed out, the plastic riser for the cables sits right in the middle of the drainage channel, so there will be some blockage of the flow to the bilge sump.

You fellows have it right. I think it was  @Ishmael who suggested off setting the pod so as to avoid the drainage channel. I kinda like that idea.

One thing I'm wondering about is a backing plate. I think it will also need to be a "compensation block" from the other side. Maybe a glob of MarineTex flat on top?

 

[jdege]

What I'd envision, in the inside of the hull, is something like a mirror of the compensation block.

A block shaped to match the hill, perhaps, in plywood, then glassed in, and covered with a backing plate.

But is there a reason you couldn't shape the block with limber holes running through it?

 

[Crash]

So I'm just spitballing here, but...an inboard diesel with saildrive has the motor mounted to two long blocks of wood that are themselves adhered to the hull, and then glassed (tabbed) to the hull to spread the thrust loads from the engine/saildrive combination to the hull.  

That compensation wedge doesn't look to have enough surface area to spread the thrust loads over a large enough area to me...I'd want maybe a piece of 3/4 in ply that was maybe 6in x 18in  or maybe 2 1/2in thick ply pieces, the first one 6 x 18, and the second maybe 4 x 12 (inches)  aligned fore and aft to help distribute thrust loads. 

 I'd also put an epoxy fillet under the ply to make a level mounting surface if mounting on centerline.  If off set, I'd still set the ply in an epoxy fillet bed, and then maybe make a smaller fillet on top to make a level surface for the nuts/washers...

Zonks, or one of the other actual Naval Engineering types can tell me I'm overthinking it...which is of course, entirely possible, and maybe even likely.    

 

[DDW]

I'd never encapsulate plywood in a boat, ever. All you need inside is a flat spot for the nuts. That could be done with just thickened epoxy, personally I'd use some blocks of G10 shaped somewhat to fit the valley - don't need to be a perfect fit at all - then bed them in thickened epoxy. Then I'd poor some filler behind it, troweled to level with the flat spot and sloping downhill from the limber hole in the aft bulkhead. Epoxy filled with a light weight filler would be fine, or foamed epoxy. Now any water will flow over and not get trapped, you won't always be looking at it when it's hauled and explaining to everyone that no, you didn't f**k up, you really meant it to be ass-sideways, and the extra work will take you about an hour.

Also keep in mind, you really just need two flat spots of the bolts, and they don't have to be the same flat spot at the same level. The wiring conduit you want standing above it all (and any water in there) anyway. 

 

[Bull City]

A lot to take in. Thanks very much. I’ll keep y’all posted. I’m still waiting for some answers to product questions from the eProp dealer. Seem like nice people. 

 

[Zonker]

Let's not forget the thrust of this motor is around 100 lbs. Like a small 4 HP outboard. Think of how much material is in a dinghy transom...This is how I'd approach it.

T

The extra layers of glass are optional and depend on how thick your hull is. But the bolts should be mostly in tension (from the thrust moment) and secondarily in shear. You just have to keep them from pulling through the hull when you hit a big log.

 

[Bull City]

The other thing I'm working on is how to fit everything into the space under the cock pit, and just aft of the companionway.



I'm thinking of mounting the pod to the aft end, kind of between the through hulls, possibly off set a little bit. Then I would fabricate a flat platform for the battery, control unit, and charger, that would occupy the space forward of the through hulls. My inner anal retentive self says that the 100+ lb. battery should be on the centerline, but there would be some benefit in placing it to one side. The real estate gets pretty tight. Thoughts?

The horizontal space forward of the through hulls is about 26" side to side X 23.5" fore & aft. The footprint of the components are:

• Battery 21.85" X 17.32" (15.35" without removable handles; plugs, indicators & controls on 21.85 front). I don't think it has mounting holes; waiting to get that answered. In the absence of mounting holes, I would have to include some structure to contain the battery while the boat heels.
  

The other components have mounting holes:

• Control Unit 9.25" X 5.10" (cables on either side of long side)
  
• Charger 235*175 9.25" X 6.88" (wires from both narrow sides)
  

I need to arrange it so the connected cables aren't overly tortured.

 

[Bull City]

Let's not forget the thrust of this motor is around 100 lbs. Like a small 4 HP outboard. Think of how much material is in a dinghy transom...This is how I'd approach it.

T View attachment 418861

The extra layers of glass are optional and depend on how thick your hull is. But the bolts should be mostly in tension (from the thrust moment) and secondarily in shear. You just have to keep them from pulling through the hull when you hit a big log.

@Zonker , this very helpful. Thank you. When you look at the drawing of the boat, like at post 102, can you determine the thickness of the hull? I've got some other drawings, but I don't know enough to tell.

The pod would be 1.5 to 2 feet behind the keel, so hitting a log would be unlikely.

 

[Zonker]

Logs sometimes hit a keel, bounce along sideways and then bang the hull a bit. Here in the great Pacific SouthWest, we have lots of experience with logs.

I'm sure the thickness shown on the drawing is just a nominal to show thickness. When you drill the first bolt hole, look at the thickness of the hull then. If less than say 4mm (3/16") add some reinforcement patches. Don't have to be huge - 3" or so across. It's just to stiffen up the hull locally so it doesn't flex.

 

[Bull City]

@Zonker Thanks. Will do.

 

[DDW]

His photos indicate quite a bit of wine glass to the shape right at the CL. That's why I'm thinking on CL. Otherwise you are mounting on quite a slope, unless you go really off center. On the other hand you don't have to fill very much of that wine glass to make the flat spot. Further, the section drawing way back shows pretty good slope coming forward, so you don't have to mount it very far forward of the bulkhead to still get a downhill run from the limber hole to the flat spot which would be filled for drainage. Again on the outside, you'll have to shape that block with a serious slope if only a little off center. If on center, it'll have a ditch through it, to match but symmetrical and won't try to climb up the side when you tighten the bolts. Also, the wineglass at the CL makes it already pretty stiff there. Less so the further off CL you go. 

 

[weightless]

Turns out the class has scanned some of the drawings and layup: https://h-boat.org/en/documents-rules/drawings

I suspect discovering as built right where you need to know will happen just after the drill is removed. The guy poking laminate into the mold may or may not have had his Wheeties that morning but I'm sure they got in the general neighborhood of spec.

 

[TwoLegged]

I'm thinking of mounting the pod to the aft end, kind of between the through hulls, possibly off set a little bit. Then I would fabricate a flat platform for the battery, control unit, and charger, that would occupy the space forward of the through hulls. My inner anal retentive self says that the 100+ lb. battery should be on the centerline, but there would be some benefit in placing it to one side. The real estate gets pretty tight. Thoughts?

The horizontal space forward of the through hulls is about 26" side to side X 23.5" fore & aft. The footprint of the components are:

• Battery 21.85" X 17.32" (15.35" without removable handles; plugs, indicators & controls on 21.85 front). I don't think it has mounting holes; waiting to get that answered. In the absence of mounting holes, I would have to include some structure to contain the battery while the boat heels.
  

The other components have mounting holes:

• Control Unit 9.25" X 5.10" (cables on either side of long side)
  
• Charger 235*175 9.25" X 6.88" (wires from both narrow sides)
  

I need to arrange it so the connected cables aren't overly tortured.

Bull, I still like my idea of mounting the battery on a cradle which is mounted to slides on the bunk fronts.  That way if you want access to the pod mountings or the cockpit drains, the the battery can be easily slid out and removed.  It would also allow a different battery to be fitted in future, simply by modifying the cradle..

I don't think that the design and construction of the cradle would require any great skill.