Torqeedo Attachment
From MarineWiki
Head line
Attaching an outboard engine to an infatable canoe.
The Story
Feb 2009 - The story begins with Mr. Jacob Manimeleth, a well known business man, called us a few months back in Feb 2009, when he thought of attaching an outboard engine to his inflatable canoe and yes he specifically said about attaching Torqeedo [1]. We said a quick Yes hoping we can make it really quick. After two weeks we got the inflatable. It was a Star inflatable model AC 300 .It didnt had a rigid transom.
March 2009 - Mean while we inquired about attaching the outboard engine to both Torqeedo and Star Inflatables. Torqeedo replied. The content was like this - “ You can only attach our Torqeedo Ultralight to an inflatable but that too is difficult”. And Star Inflatables? They didn't reply at all !!!.We searched for existing desings in internet. We found some. But most of them had rigid transom. Some were with out a rigid transom but the details of those were not available.We realized that we are not going to get an existing design. So we decided to get back to the basic principle and design a new attachment ourselves. We began to design one. The design was not so complicated as it was a case of simple bending with a couple at one end. But we need the dimensions. For that we decided to fill air in the inflatable so that we can take dimensions. We tried to do it with a foot pump which proved to be a very difficult task. But the rest was a good example of our team work. Although we were not able to build the required pressure in the inflatable, we succeeded in giving the inflated shape which was sufficient for taking the dimensions. One of the picture shows the outcome of our team work. We got the dimensions. We started designing the attachment. The out come of the design is shown in the picture below. The base frame consists of two aluminium rods (6061 T6) and a transom of the same material clamped to the rod. Two clamps were provided at the forward end of the attachment for fixing it to the aft seat of the inflatable. The rods are supported by two polyurethrene clamps as shown in the pic.We ordered for Torqeedo. It took 4 weeks to get that in our hands (It took more time for the clearence of the battery because it comes under the category of dangerous goods). Mean while we had to take a break and a couple of holidays came in between. So time moved on with out any further progress.
April 2009, Second Week - We got the torqeedo. We had the design of attachment already.we decided to conduct a test using a temporary set up on that sunday. We did it in a big pond by using a temporary structural arrangement. It was a great experience. We identified some of the drawbacks in our design like the tiller arm didnt had sufficient length. This insufficient length caused an inconvenient sitting posture.This we informed our client and ordered for a tiller arm extension So everything is easy.We ensured our client that everything will be done by the end of the month.We didnt realized it going be tough from that point onwards. One of the pictures of first trial is shown. We began to search for the required material and aluminium welders. We called several aluminium dealers. Unfortunately none of them had the material we required !!! Nobody had the required clamp either. We searched for aluminium welders also. That also ended up with out any positive results.The market seemed to be a desert for us. Time moved on. We lost hope in fabricating an aluminium structure.The heat was building up.
April 2009, Third week - We decided to use stainless steel instead of aluminium for the attachment. We found out stainless steel welders.Our plan was to complete fabrication by saturday and do the second testing with the real attachment on sunday, that week. We also had to arrange life jackets for our second testing.We identified the stainless steel dealers and life jacket dealers and started material procurement on Thursday. The D day was Friday. By noon we started fabricating the Torqeedo attachment.
Fabrication
Fabrication was done in the production facility below our office.The equipments required were stainless steel cutter, Grinder, Welding equipment, Drilling machine and the related consumables. First we cut the hollow shafts in to the required dimensions and welded it and made the base structure. And then we made the transom with stainless steel plates and welded it to the base frame. We didnt get the required clamp which we intended to use in the forward end of the attachment (refer picture of model), we decided to cut two stainless steel plates and bolt it to the existing seat bolts.That can be observed in the figure.But We could only finish up to the base structure fabrication on the same day. We were waiting patiently for the next day and that was a lengthier night. At last friday came.We smelled victory.After the structure is fabricated, it is finished by buffing. Buffing is a finishing process used for smoothing a work piece using an abrasive and a work wheel. The process gave us a smooth finish. After buffing we attached the attachment to the inflatable to see what it looks like. It was great relief and was a happiest momnet for us. We completed the Torqeedo attachment fabrication. The attachement looked like an integral part of the canoe. See the picture.
Second trial
We have done the second trial with the real attachment at Triprayar river on that sunday as planned. It was again a great experience. We hope our client will be happy with the whole thing.A picture of the second trial is given at the end of the story. To see the video click here.
End of the day
Pros
- Was able to attach a torqeedo travel 801 successfully to an inflatable. Normally these type of engines are not match for such an inflatable.
- The attachment proved to be healthy and have the capacity to hold the high thrust developed by the torqeedo.
- Less wastage of material.
- The attachment is fully detachable.
- Alteration made in the basic product is nil.
Cons
- The structure is heavier because of the use of Stain less steel and it causes an initial trim by aft.
- The trim become extremely high when someone comes to the aft extreme provided there is more than one person in the inflatable on the seats.
- The tiller arm is not reachable which will be corrected by providing a tiller extension soon.
- At higher speeds the transom of the structure goes below the water which seems to create an obstruction in the flow to the propeller.
- Higher speed causes much excited vibration.
