Sweetlip
16-10-2013, 06:50 AM
A very frequent question to be found on pretty well every online fishing forum on the planet relates to how to mount a bow mount electric trolling motor without having to cut the bow rails on a boat. An also very frequent question arises as to whether mounting a bow mount is viable on a runabout, especially in relation to there being enough deck space in front of the windscreen for the bow mount to lie in its reclining, at rest, position.
There is, of course, no definitive answer to these questions as every boat design is different. However, this post seeks to add just a bit more to the body of knowledge on these topics by showing how I have installed my new 80 lb thrust, 24V, 54 inch, iPilot Minn Kota Bow Mount, so as to help others who might be Googling these questions. I am not saying that this is the ideal way of installing a bow-mount without cutting the bow rails; it is just the way that I have done it.
Whilst the question about how to avoid cutting bow rails when installing a bow mount gets asked a lot, there are few responses on the internet as to how this may be done. Some bow rails are high but have a big gap at the bow sprit where sometimes people have mounted a raised base for their trolling motor such as may be found here ... http://www.fishraider.com.au/Invision/index.php?showtopic=29655 Some have just bolted a big lump of wood on their front deck on which to mount the trolling motor base in a way that clears the rails. Others have made up some sort of mechanical support to straddle the bow rails such as the one shown in the post by RayLamp in this thread... http://www.ausfish.com.au/vforum/showthread.php?189471-Minn-Kota-Bow-mount-to-Quintrex-Coastrunner-4.55.
However, I was inspired by a version showing a trolling motor mounted on the bow rails themselves in this post ... http://www.fishtheclassic.net/forums/showthread.php?14498-Bow-mount-trolling-motor-on-a-170-Open& and so I thought that I might give that method a go.
My boat is a 12 year old Quintrex 4.75m Bay Hunter Caprice. This model has a couple of features that lend themselves to such a style of bow mount installation. The first is that the bow rails are quite low and with a flattish profile so that the amount of shaft height lost by mounting the motor on the rails instead of on the front deck would be only about 200 mm.
The second is that as this boat has a walk-through windscreen, the distance of the windscreen from the bow is just a little more than the equivalent model without the walkthrough facility. That allows just that little more distance available for the electric motor to rest in its reclining position. More on that later.
My solution was simply to mount a small platform on the bow rails on which to mount the Minn Kota.
The little platform comprises two layers of 3/4" plywood glued together and another layer of pieces of Tassie Oak glued underneath. Under the top platform, everything is machined to the curves of the rails and bevelled such that when pulled forward, the whole shebang wedges into the rails and is secured in place primarily with a couple of brackets fashioned out of aluminium bar to wrap around the rails. A couple of light plastic rail brackets have been added at the front for minor additional support, chiefly to hold down the flat platform to the front of the rails which slope downward at that point.
Plan A has been to use this plywood arrangement as a prototype for an eventual all-aluminium construction but I may just get lazy about that for a while. The wooden parts have been given a couple of coats of epoxy wood preservative. The top platform has been edged with Tassie Oak so no plywood edges are open to the elements and, as you can see, it has all received a few coats of paint. It should handle weathering for quite a while.
Obviously, I do lose some user friendliness in respect of retrieving the anchor over the front bow roller and under the Minn Kota's mounting platform but it should still function, even if not in an ideal way, and hopefully, I won't be anchoring too often with the Minn Kota in use, anyway.
I have mounted the Minn Kota on the optional Minn Kota quick release bracket arrangement on the mounting platform. That quick release bracket allows the removal of the unit from the boat, easily, simply by pulling out a locking handle. However, even so, this model is not so light and it is quite ungainly an activity, even for a big bloke like me, to manhandle the Minn Kota on and off the boat on a ladder. So I am leaving it in place, secured with a stainless steel padlock.
I view this as a prototype installation at this stage, just to see if the idea of mounting the trolling motor on my aluminium rails, instead of the standard method of on a bracket welded to the deck, and with ugly cutting of the rails, is viable. My main concerns have been:-
(a) if the length of shaft is adequate - I can get a longer shaft if necessary. That should only be necessary if the ups and downs at the bow in rough seas cause the prop to cavitate. A longer shaft, however, may cause some issues for the reclining, stored position of the Minn Kota in that it might be a tight squeeze at the windscreen end.
(b) whether the aluminium rails would handle the 24V, 80 lb thrust, trolling motor under full power. On this latter issue, it is the deflection of the rails that have been my primarily concern. The guiding example mentioned above was on a boat with stainless steel rails so I have been wondering how the aluminium rails will perform. My quick solution, if it were necessary, would be be to add a couple of stanchions to support the mounting platform to the deck to take some pressure off the rails.
I took the boat for a three hour slow speed cruise around Manly Boat Harbour yesterday to water-test the arrangement and in the calm waters of the harbour the trolling motor performed well. However, I did take the boat outside the harbour and when a few bow waves from passing boats gave me some ups and downs at the bow, the prop did get more air than I would like so I shall change the 54" leg into a 60" one, which is the biggest that they sell. I understand that such changeover is a $150 exercise but it is better to do that now while I am setting it all up than later when I might not have as much enthusiasm for doing the work or taking the motor in to the agent.
As mentioned, though, that extra 6 " will make things a bit tight at the windscreen end when the motor is in its reclined, resting position as shown below. However, that is not an insurmountable problem as I shall just install the motor a bit more forward on its mounting platform, even if I need to add another plywood plate on top of the mounting platform.
My concerns about the load on the aluminium bow rails were not worth having. I saw no deflection of any particular note in the rails. I was surprised to see, however, deflection in the plywood platform itself when the motor was under full power, but not enough to cause any concern. That deflection did surprise me as the total thickness of wood is 42 mm and there are two aluminium brackets under that. It is not worth making any effort to strengthen that other than by, perhaps, adding two or three bolts along the length of the rear aluminium bracket to make it a more rigid coupling to the platform. I did hit the full power button a few times and yes, on a 24V machine, that certainly gives it a jolt of energy but nothing bad happened in the mounting arrangements as a result.
On the next post, I shall add a few details about other aspects of this installation, in relation to the batteries etc but so as to collate all of the relevant pictures into one post, here endeth the story.
There is, of course, no definitive answer to these questions as every boat design is different. However, this post seeks to add just a bit more to the body of knowledge on these topics by showing how I have installed my new 80 lb thrust, 24V, 54 inch, iPilot Minn Kota Bow Mount, so as to help others who might be Googling these questions. I am not saying that this is the ideal way of installing a bow-mount without cutting the bow rails; it is just the way that I have done it.
Whilst the question about how to avoid cutting bow rails when installing a bow mount gets asked a lot, there are few responses on the internet as to how this may be done. Some bow rails are high but have a big gap at the bow sprit where sometimes people have mounted a raised base for their trolling motor such as may be found here ... http://www.fishraider.com.au/Invision/index.php?showtopic=29655 Some have just bolted a big lump of wood on their front deck on which to mount the trolling motor base in a way that clears the rails. Others have made up some sort of mechanical support to straddle the bow rails such as the one shown in the post by RayLamp in this thread... http://www.ausfish.com.au/vforum/showthread.php?189471-Minn-Kota-Bow-mount-to-Quintrex-Coastrunner-4.55.
However, I was inspired by a version showing a trolling motor mounted on the bow rails themselves in this post ... http://www.fishtheclassic.net/forums/showthread.php?14498-Bow-mount-trolling-motor-on-a-170-Open& and so I thought that I might give that method a go.
My boat is a 12 year old Quintrex 4.75m Bay Hunter Caprice. This model has a couple of features that lend themselves to such a style of bow mount installation. The first is that the bow rails are quite low and with a flattish profile so that the amount of shaft height lost by mounting the motor on the rails instead of on the front deck would be only about 200 mm.
The second is that as this boat has a walk-through windscreen, the distance of the windscreen from the bow is just a little more than the equivalent model without the walkthrough facility. That allows just that little more distance available for the electric motor to rest in its reclining position. More on that later.
My solution was simply to mount a small platform on the bow rails on which to mount the Minn Kota.
The little platform comprises two layers of 3/4" plywood glued together and another layer of pieces of Tassie Oak glued underneath. Under the top platform, everything is machined to the curves of the rails and bevelled such that when pulled forward, the whole shebang wedges into the rails and is secured in place primarily with a couple of brackets fashioned out of aluminium bar to wrap around the rails. A couple of light plastic rail brackets have been added at the front for minor additional support, chiefly to hold down the flat platform to the front of the rails which slope downward at that point.
Plan A has been to use this plywood arrangement as a prototype for an eventual all-aluminium construction but I may just get lazy about that for a while. The wooden parts have been given a couple of coats of epoxy wood preservative. The top platform has been edged with Tassie Oak so no plywood edges are open to the elements and, as you can see, it has all received a few coats of paint. It should handle weathering for quite a while.
Obviously, I do lose some user friendliness in respect of retrieving the anchor over the front bow roller and under the Minn Kota's mounting platform but it should still function, even if not in an ideal way, and hopefully, I won't be anchoring too often with the Minn Kota in use, anyway.
I have mounted the Minn Kota on the optional Minn Kota quick release bracket arrangement on the mounting platform. That quick release bracket allows the removal of the unit from the boat, easily, simply by pulling out a locking handle. However, even so, this model is not so light and it is quite ungainly an activity, even for a big bloke like me, to manhandle the Minn Kota on and off the boat on a ladder. So I am leaving it in place, secured with a stainless steel padlock.
I view this as a prototype installation at this stage, just to see if the idea of mounting the trolling motor on my aluminium rails, instead of the standard method of on a bracket welded to the deck, and with ugly cutting of the rails, is viable. My main concerns have been:-
(a) if the length of shaft is adequate - I can get a longer shaft if necessary. That should only be necessary if the ups and downs at the bow in rough seas cause the prop to cavitate. A longer shaft, however, may cause some issues for the reclining, stored position of the Minn Kota in that it might be a tight squeeze at the windscreen end.
(b) whether the aluminium rails would handle the 24V, 80 lb thrust, trolling motor under full power. On this latter issue, it is the deflection of the rails that have been my primarily concern. The guiding example mentioned above was on a boat with stainless steel rails so I have been wondering how the aluminium rails will perform. My quick solution, if it were necessary, would be be to add a couple of stanchions to support the mounting platform to the deck to take some pressure off the rails.
I took the boat for a three hour slow speed cruise around Manly Boat Harbour yesterday to water-test the arrangement and in the calm waters of the harbour the trolling motor performed well. However, I did take the boat outside the harbour and when a few bow waves from passing boats gave me some ups and downs at the bow, the prop did get more air than I would like so I shall change the 54" leg into a 60" one, which is the biggest that they sell. I understand that such changeover is a $150 exercise but it is better to do that now while I am setting it all up than later when I might not have as much enthusiasm for doing the work or taking the motor in to the agent.
As mentioned, though, that extra 6 " will make things a bit tight at the windscreen end when the motor is in its reclined, resting position as shown below. However, that is not an insurmountable problem as I shall just install the motor a bit more forward on its mounting platform, even if I need to add another plywood plate on top of the mounting platform.
My concerns about the load on the aluminium bow rails were not worth having. I saw no deflection of any particular note in the rails. I was surprised to see, however, deflection in the plywood platform itself when the motor was under full power, but not enough to cause any concern. That deflection did surprise me as the total thickness of wood is 42 mm and there are two aluminium brackets under that. It is not worth making any effort to strengthen that other than by, perhaps, adding two or three bolts along the length of the rear aluminium bracket to make it a more rigid coupling to the platform. I did hit the full power button a few times and yes, on a 24V machine, that certainly gives it a jolt of energy but nothing bad happened in the mounting arrangements as a result.
On the next post, I shall add a few details about other aspects of this installation, in relation to the batteries etc but so as to collate all of the relevant pictures into one post, here endeth the story.