Drilling a Hole!

[Naughty Cal]

To fit the new chart plotter and connect it all up to the sonar module and transom mount transducer we will have to drill a fairly decent sized hole in the transom of the boat to thread the wiring and connection plug through from the outside of the boat into the engine bay.

 

The transducer will fit between the drive and the trim tab about three inches from the trim tab and level with the bottom of the hull.

 

 

 

The cable will come higher that the water line as the trim tab cables currently do and the hole will be covered over with a stainless steel clam shell cowl similar to this:

 

https://www.gsproducts.co.uk/45mm-43mm-stainless-steel-shaped-vent/

 

But what do we fill the hole around the cable with?

 

The hole will be considerably larger then the diameter of the cable due to the size of the end connector on the tranducer cable which according to the manufacturer can not be removed from the cable nor the cable cut to size. 

 

So is there a product that can surround the cable and bung the hole?

 

 

[Tony Brooks]

Split rubber grommet? I don't see why careful masking and application of something that sets to a rubbery consistency like silicon would not do.

[Naughty Cal]

It probably would do to be honest.

 

It won't be under the waterline, it will be on the lip where the trim tab wires enter the boat so it would only really need to keep splashes of water out.

[Tony Brooks]

I would be tempted to wax the inside of the clamshell and fit it. Then mask right over the hole on the inside with the paper as tight as possible. The get very messy squirting silicon or similar up into the clamshell and pushing it against the masking, leaving an  un-siliconed area at the bottom of the clamshell so you can not see the inevitable somewhat rough surface..

[Alan de Enfield]

17 minutes ago, Naughty Cal said:

To fit the new chart plotter and connect it all up to the sonar module and transom mount transducer we will have to drill a fairly decent sized hole in the transom of the boat to thread the wiring and connection plug through from the outside of the boat into the engine bay.

 

The transducer will fit between the drive and the trim tab about three inches from the trim tab and level with the bottom of the hull.

 

 

 

The cable will come higher that the water line as the trim tab cables currently do and the hole will be covered over with a stainless steel clam shell cowl similar to this:

 

https://www.gsproducts.co.uk/45mm-43mm-stainless-steel-shaped-vent/

 

But what do we fill the hole around the cable with?

 

The hole will be considerably larger then the diameter of the cable due to the size of the end connector on the tranducer cable which according to the manufacturer can not be removed from the cable nor the cable cut to size. 

 

So is there a product that can surround the cable and bung the hole?

 

 

If I remember correctly you need to ensure that the transducer is not going to be in any 'disturbed' water (either by the hull shape, the prop or the trim tabs) as any air bubbles will affect the performance.

From looking at pictures of you up on the plane it looks as if you may have a lot of 'airy' water at the back-end.

 

With regard to getting a water tight seal around the cable, I used these 'deck glands' when I fitted the Radar cable and that had huge connectors.

Available in a wide variety of sizes.

 

https://www.force4.co.uk/department/electrical/plugs-sockets-deck-glands/deck-glands.html

 

 

Edited February 20, 2019 by Alan de Enfield

[NB Esk]

I'd want to use a good quality sealant, such as Sikaflex or Marineflex.  Mask up the bottom of the hole, using the masking to keep the cable central and then fill from the top, using gravity to help.  Should result in a neat job....

 

 

 

[Jen-in-Wellies]

What diameter hole is needed for the connector to fit through?

[Naughty Cal]

1 minute ago, Alan de Enfield said:

If I remember correctly you need to ensure that the transducer is not going to be in any 'disturbed' water (either by the hull shape, the prop or the trim tabs) as any air bubbles will affect the performance.

From looking at pictures of you up on the plane it looks as if you may have a lot of 'airy' water at the back-end.

 

With regard to getting a water tight seal around the cable, I used these 'deck glands' when I fitted the Radar cable and that had huge connectors.

Available in a wide variety of sizes.

 

 

Yes the down vision is not going to be of any use when the boat is on the plane. But in open water we will want the screen on the charts anyway and have the Tridata to give the water depth.

 

The sonar and down vision will only really be of any use when we are pootling along. 

 

From conversation with others with similar boats and transducer set ups also with limited space to fit the transducers on the stern it can be a bit hit and miss and is very reliant on hull shape and spray rail locations as well. 

 

Current thinking is that the best location for it will be approx. 3 inches from the starboard trim tab with the transducer level with the low side of the v of the hull. This should clear the spray rails, disturbance from the trim tab and keep it clear of the prop disturbance in forward gear at least.

4 minutes ago, Jen-in-Wellies said:

What diameter hole is needed for the connector to fit through?

Not got the cabling on me it's at home but it is in the order of 20mm. 

[Jen-in-Wellies]

Something like this? Made for passing a car wiring loom with lots of connectors on the end through the engine compartment steel panel. A similar situation, but you might need to thin the GRP, or have it in a small aluminium panel glassed in to the GRP as it is designed to clip in to a steel car panel. STick it in hot water to make it soft enough to go over the connector.

 

Jen

Edited February 20, 2019 by Jen-in-Wellies

[Keeping Up]

In a similar situation our boatbuilder stuck some tape on one side then sprayed on the other side (which was very difficult to reach) with an aerosol of expanding foam. Then when it had dried he removed the tape and sprayed foam from that side too, which we later trimmed to be neater with a sharp knife.

[pearley]

1 hour ago, Jen-in-Wellies said:

Something like this? Made for passing a car wiring loom with lots of connectors on the end through the engine compartment steel panel. A similar situation, but you might need to thin the GRP, or have it in a small aluminium panel glassed in to the GRP as it is designed to clip in to a steel car panel. STick it in hot water to make it soft enough to go over the connector.

 

Jen

When I was working we would have used one of these to expand/open up the hole in the grommet to enable the plug to pass thtough.

 

https://www.ebay.co.uk/itm/HELLERMANN-TYTON-SS-FITTING-TOOL-TYPE-SS-1-2-TO-2MM-/181640228009?redirect=mobile

[Naughty Cal]

The trouble we are going to have is that getting to the transom on the inside in the engine bay is nigh on impossible!

 

On the plus side it wont have to look overly neat in the engine bay as it will never be see Unless a contortionist dwarf buys the boat at some point in the future.

[WotEver]

1 hour ago, pearley said:

When I was working we would have used one of these to expand/open up the hole in the grommet to enable the plug to pass thtough.

 

https://www.ebay.co.uk/itm/HELLERMANN-TYTON-SS-FITTING-TOOL-TYPE-SS-1-2-TO-2MM-/181640228009?redirect=mobile

I used to have one of those! And a load of Hellerman sleeving to suit. All made redundant by heat shrink tubing. 

 

You've made me wonder now whatever happened to it...

1 hour ago, Naughty Cal said:

... Unless a contortionist dwarf buys the boat at some point in the future.

I needed one of those when I needed to work on the engine on WotEver. Never managed to find one...

[Chewbacka]

You could take 2 metal strips, clamp them onto a bit of plate so they but up to each other then drill a hole slightly bigger than the cable diameter in the ‘join’.  Then fit the plates around the cable with a split grommet if required.  Bond the plates onto the panel and if you want it ‘strong’ a couple of bolts or pop rivets will hold them in place.  Then any small gaps can be sealed by sealer, body filler etc.

 

 

added - or just take a bit of plate, drill a hole about 20mm from the edge and cut a slot from the hole to the edge.  Pull the cable to the edge of you big hole then slide your plate using the slot so the plate hole holds the cable close to the edge of the big hole.  Grommets, sealing as above

Edited February 20, 2019 by Chewbacka

[Alan de Enfield]

Some excellent ideas and bodge-tips, but why bother with expanding foam, filler, tape, bits of metal when for £15-£20 the 'proper' gland can be used giving 100% water tightness and the ability to simply remove / replace the cable.

 

Spend 10's of £1000's on a boat, add £100's (£1000s) more on electronics and then scrimp on £20 to make a decent installation.

 

Its a 'smart & tidy' boat, "Don't spoil the ship for a h'path of tar"

[Naughty Cal]

17 minutes ago, Alan de Enfield said:

Some excellent ideas and bodge-tips, but why bother with expanding foam, filler, tape, bits of metal when for £15-£20 the 'proper' gland can be used giving 100% water tightness and the ability to simply remove / replace the cable.

 

Spend 10's of £1000's on a boat, add £100's (£1000s) more on electronics and then scrimp on £20 to make a decent installation.

 

Its a 'smart & tidy' boat, "Don't spoil the ship for a h'path of tar"

I agree with you entirely but the problem we are likely to have with the gland is getting access to the inside of the boat at the cable entry point.

[Alan de Enfield]

1 minute ago, Naughty Cal said:

I agree with you entirely but the problem we are likely to have with the gland is getting access to the inside of the boat at the cable entry point.

I don't know your set-up, but if you drill the hole (3/4" ?) feed the connector thru from the outside attached to a length of stiff wire (coathanger for example) can you push it thru' far enough to be able to reach it, or 'hook-it' from the inside of the engine 'ole ?

Pull it thru.

You can then cable tie it to the wiring harness and up to the instrument panel.

 

The cable connector does not go thru' the gland, the rubber insert is tapered and pushes out of its surrounding holder, the rubber insert is 'split', opens around the cable and then pushed back up into the holder, as it is screwed onto the transom the rubber gasket is trapped beneath the gland and as the screws are tightened the rubber insert is pulled up into its taper 'locking' tightly onto the cable forming a watertight seal.

 

You do not need any access to the back of the transom for fitting the gland.

[Naughty Cal]

1 hour ago, Alan de Enfield said:

I don't know your set-up, but if you drill the hole (3/4" ?) feed the connector thru from the outside attached to a length of stiff wire (coathanger for example) can you push it thru' far enough to be able to reach it, or 'hook-it' from the inside of the engine 'ole ?

Pull it thru.

You can then cable tie it to the wiring harness and up to the instrument panel.

 

The cable connector does not go thru' the gland, the rubber insert is tapered and pushes out of its surrounding holder, the rubber insert is 'split', opens around the cable and then pushed back up into the holder, as it is screwed onto the transom the rubber gasket is trapped beneath the gland and as the screws are tightened the rubber insert is pulled up into its taper 'locking' tightly onto the cable forming a watertight seal.

 

You do not need any access to the back of the transom for fitting the gland.

Got you. That sounds like it will work.

 

We will be able to hook the cable and feed that through. No worries on that score.

[Momac]

8 hours ago, Naughty Cal said:

Yes the down vision is not going to be of any use when the boat is on the plane. But in open water we will want the screen on the charts anyway and have the Tridata to give the water depth.

 

The sonar and down vision will only really be of any use when we are pootling along. 

 

From conversation with others with similar boats and transducer set ups also with limited space to fit the transducers on the stern it can be a bit hit and miss and is very reliant on hull shape and spray rail locations as well. 

 

Current thinking is that the best location for it will be approx. 3 inches from the starboard trim tab with the transducer level with the low side of the v of the hull. This should clear the spray rails, disturbance from the trim tab and keep it clear of the prop disturbance in forward gear at least.

Not got the cabling on me it's at home but it is in the order of 20mm. 

Is this much different to the arrangement for the trim table wire ? I have never needed to  work with these but if the existing trim tab cable entry uses  sealant the same principle  should be okay for the transducer 

Can the transducer and trim tab wires  share the existing cable entry /clamshell ?

[Naughty Cal]

2 minutes ago, MartynG said:

Is this much different to the arrangement for the trim table wire ? I have never needed to  work with these but if the existing trim tab cable entry uses  sealant the same principle  should be okay for the transducer 

Can the transducer and trim tab wires  share the existing cable entry /clamshell ?

No. The connector plug is far too big to go through the hole for the trim tab cables. 

 

The trim tab cables have a tiny hole as they are just wires threaded through not a big connector.

[Momac]

2 hours ago, Naughty Cal said:

No. The connector plug is far too big to go through the hole for the trim tab cables. 

 

The trim tab cables have a tiny hole as they are just wires threaded through not a big connector.

Okay. I guess you are going with the Scanstrut type gland .

 

To help running cables I have used fiberglass rods but last time  I used a length of three core shore power cable which was stiff enough to push through but flexible enough to get around corners . Then tied the new cable to the three core and pulled that through. 

 

I also used some expanding braided cable sheathing which, once in place, has made threading extra cables through the same route much easier .  I am guessing after the  transducer fitting to the transom the next challenge will be running cables up the the MFD at the helm.  

 

Did you get any  Raymarine power and network cables with the equipment ? I think you will need  a  ''Raynet'' cable between the sonar module and the MFD?

Edited February 20, 2019 by MartynG

[blackrose]

I always thought transducers could "see" through GRP? I guess that's wrong? It's that just depth gauges? As you can tell, I don't really know what I'm talking about but I'm sure I read something and thought it might be worth mentioning before any holes are drilled.

[Naughty Cal]

37 minutes ago, MartynG said:

Okay. I guess you are going with the Scanstrut type gland .

 

To help running cables I have used fiberglass rods but last time  I used a length of three core shore power cable which was stiff enough to push through but flexible enough to get around corners . Then tied the new cable to the three core and pulled that through. 

 

I also used some expanding braided cable sheathing which, once in place, has made threading extra cables through the same route much easier .  I am guessing after the  transducer fitting to the transom the next challenge will be running cables up the the MFD at the helm.  

 

Did you get any  Raymarine power and network cables with the equipment ? I think you will need  a  ''Raynet'' cable between the sonar module and the MFD?

Yes we have the Raynet cables. 

 

Depending on where we can locate the sonar module though we may need a longer one for between the sonar module and the MFD.

31 minutes ago, blackrose said:

I always thought transducers could "see" through GRP? I guess that's wrong? It's that just depth gauges? As you can tell, I don't really know what I'm talking about but I'm sure I read something and thought it might be worth mentioning before any holes are drilled.

Depends on the transducer.

 

Our current speed, depth and temperature transducers are both through hull fittings.

 

The new one is a transom mounted unit so it is only a hole for the cabling.

[Alan de Enfield]

38 minutes ago, blackrose said:

I always thought transducers could "see" through GRP? I guess that's wrong? It's that just depth gauges? As you can tell, I don't really know what I'm talking about but I'm sure I read something and thought it might be worth mentioning before any holes are drilled.

 

Yes they can but it is quite a complex installation.

 

There must be absolutely NO air gap between the transducer and the GRP (and hopefully no air bubbles in the GRP lay-up)

You need to have a length of plastic pipe fibreglassed to the hull.

The pipe has to be filled with oil and then the transducer installed into the oil filled tube and capped off so the oil does not spill out.

 

It does work but the signal is attenuated in comparison to being in 'open-water'

 

Most boats have a thru-hull fitting in which the transducer 'clips', the transducer can be removed for cleaning / maintenance and a 'bung is supplied which caps off the 'hole' whilst working on the transducer.

[Momac]

12 hours ago, Naughty Cal said:

 

 

 

Raymarine  products are a bit odd in that all their products are not necessarily compatible with each other .... especially when mixing current and legacy products.

I googled the transducer and it came up with that looking like a CPT-60  transducer for certain Dragonfly products? Or perhaps you have an adapter ..?

Edited February 20, 2019 by MartynG