The boat is getting on plane easy with 2 adults and 1 child+gear, on 6hp=4.4kw.
I am not sure how marine motors are rated, at the motor or at the prop? I guess it should be similar to 5kw electrical.
I have lots of e-motors that could fit on an old outboard chassis, but it will probably be very noisy and not so efficient. Having the motor under water sorts the cooling and noise issues.
My plan at the moment is a single flipsky 161 inrunner on a gong alu mast, and printed/plywood transom mount
I have always understood outboard gas powered motors HP is measured at the prop. Like anything else that has various ways of doing things you might get someone else saying it’s at the crankshaft.
IMO at prop is more accurate as it takes into account reduction gears etc that might be in the drive train.
In my personal experience I had a small Zodiac hull (about 2 meters) and I used a small trolling motor powered by a 12V battery that moved it around efficiently. (Not planing but good cruising speed). I eventually replaced that with a 4HP 2 stroke gas motor with a Doyle fin mounted and it would plane the hull off with 2+ adults at speeds that weren’t comfortable in choppy water.
Gas motor weight is more of a factor in a small boat like this often requiring crew weight move towards bow to get planing. Some people position gas tank on bow to compensate.
The fin really helped ? I heard mixed things about it, sure it could help the back of the boat but mostly create more drag and reduce top speed? The extra lift help to get on plane with more load?
Here is the boat with just me aboard. The motor is on the rev limiter (even with 2+ person), so it could go faster with a higher pitch prop I guess.
The fuel tank in the front helps, also some tiller extension.
I will run more tests with the gaz motor, to have the towing rope and anchor point for tow sorted out while I work on the E-motor, then figure out the remote steering control.
In the first session , I had trouble to figure out how to foil start, with a small 24lt board. Not really enough power for a deep water start, and starting on my belly I had trouble to transition to standing.
I have a tow-in session planned in MAY, I will go with the ICE and assist motor as backup for now.
This motor option seems interesting, even if the prop guard may not be the most efficient.
The Doyle fin helps in popping boat onto plane earlier and also where you sit once planing as I notice you are midship and arm extended to run tiller. Very tiring if there is any bouncing due to chop. With Doyle you might still have to shift weight forward at early stage of plane off but can then move back and almost sit beside motor. Front of these hulls make quite bit of fine spray in chop so passengers get wetter if they are sitting forward.
Top speed impact I’m not sure. Lot of drag from air inflated material vs gelcoat finer hull so not sure the Doyle fin has any significant impact on top speed. It does allow maintain plane at lower
speeds so extends range when you don’t want or need to go WOT.
The commercial product isn’t highly refined so you could likely print something much better of drag is an issue.
Have you looked at Torgeedo specs for data? Might be useful in planing stages.
I have seen some very impressive videos from 4.0 torquedoo system on a SIB :
Unfortunately, not easy to find second hand and not in production anymore as far as I understand.
For now I am preparing the assist system integration as a trolling motor to get around on lakes where ICE is prohibited and use the boat as a pump start platform. Using my existing system, bike parts, available 6374 with triblade, minimal investment for a low power (max 1500/2000W) system.
The part I am really not sure about is how to mount the outboard to the transom, any outside ideas would be welcome!
AliExpress has outboard motor mounts.
Maybe with some small modifications it might work for you?
Perfect, thank you! did not find those in my search
Maybe find a used or damaged trolling motor and salvage the mount from it.
Tilt is important as you can leave drive unit on while beaching the boat.
The mount proposed by @kian has the tilt system and adjustment of the motor angle. However I can not figure out or find the diameter of the clamp.
Chatgpt says 68-68mm based on the M6 screws heads, two different photos analysed. Hard to find any info online…
Use with a bigger controller box mounted on top in the future :
Inside the streamlined profile there is a 50x12x2mm alu profile for strength, and avoid a fiberglass job on the outside.
After manual checks I think the diameter must be close to 50mm, and the length of the mount around 168mm
Adapt the mount
Waou ! Adam Excellent project ! I had the same idea for this summer !!! amazing !
Congrats on progress!
Have you considered getting a launch dolly? This one in vid is obviously too big but nice folding design
See customer feedback: 'https://www.aliexpress.us/item/3256806835769770.html
Same bracket used with 48V 4HP electric outboard
'https://www.aliexpress.us/item/3256806811650821.html
Wow, thanks !
I will be able to keep on printing the rest of the system with this information.
