The helm of the Teleflex "Rack" system is designed to fit under a dash board, with the steering wheel attaching directly to it. It comes with optional wedge fittings, so that there can be a 90° connection, or 80° or 70°. Obviously the angle of the dash board and the comfortable angle of the steering wheel determine the appropriate fitting to use.
The Teleflex helm, showing the tapered end which accepts the wheel, and the black bezel which attaches to the dash.
In the case of the traditional slipper launch, there is no dash board, (although the Selway-Fisher design appears to accommodate one). Instead, the wheel attaches to a steering column which passes through the dash bulkhead and the steering mechanism is located in the motor compartment. The column itself is supported by two bearings which are held by the bottom frame of the windscreen and by the bulkhead.
Until such time as the windscreen was built and some sort of temporary driver's seating installed I had no way of knowing the angle at which the column would penetrate the bulkhead, so I chose the 90° fitting for the helm in the expectation of having to construct a false dash board to hold the helm in the motor compartment. That moment has now arrived, so the task at hand is to introduce a mock steering column and wheel and test them for comfort. After that, an angled box of sorts can be built and attached to the forward side of the bulkhead such that the steering column will pass into the box and be fixed to the helm.
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61. Finishing the Transom
With the deck framework complete it is time to finish the mahogany outer strip of the transom. Until now I have been unable to determine the correct cut for the top of the strip, where it meets the deck. But now I can place a piece of ply over the rear end of the deck frame and trim it to the exact shape of the inner laminations of the transom. The mahogany will tuck up next to the ply and finish flush with its upper surface. The second deck skin in this area will be the transverse arm of the covering board, which will sit on top of both the ply and the transom.
To measure the height of the mahogany transom piece, the ply is only screwed to the deck frame, and not glued, because I need to be able to clamp the mahogany in place while its glue is drying. So, with the ply trimmed to shape and fixed down temporarily, the mahogany strip is held against the transom and scribed to the top of the ply. It is cut to size and the ply is removed. The mahogany is glued to the transom, and when the glue is dry the ply is returned and the final trimming of the mahogany is done, ensuring that it stays exactly in line with the ply so that there will be no visible gaps or glue lines between it and the covering board.
But before any of that can happen there has to be an angled trim piece added to the top of the transom, which has been cut horizontally. The ply subdeck needs something to rest on, so a triangular section strip is added.
The idea is to add a triangulated filler to the top of the transom.
It has to be steamed to accept the bend, and the poor man's steam box does the trick, as it did with the stem timbers. Then the piece is clamped into position and left for a day to accustom itself to the curve it has to negotiate before the glue is laid down.
Steaming and bending the trim on the top of the transom frame.
The final glue up is a riot of clamps and wedges to keep the piece both curved and flat.
This step has been a lot of
fiddle, just as the cambering of the transom inner frame was, and it
could all have been avoided if I had been prepared to accept the
cut-off straight stern of the original plan. But I think that it was
all worth it when I look at the shape which is appearing now and
compare it with the unaltered forms.
After removal of the clamps, and trimming of the new piece, there is a smooth seat for the subdeck to rest on. The gap behind the trim on top of the transom will be filled with epoxy in due course, which will cement the joint between the mahogany outer lamination of the transom and the subdeck.
The finished transom trim.
After removal of the clamps, and trimming of the new piece, there is a smooth seat for the subdeck to rest on. The gap behind the trim on top of the transom will be filled with epoxy in due course, which will cement the joint between the mahogany outer lamination of the transom and the subdeck.
The finished transom trim.
The ply is marked to approximate size on the boat and trimmed with overhang. The forward end is aligned with the hatch opening, and a washered screw is placed through it into the bulkhead F top frame at its centre to hold it there. Screws are then introduced over the central deck stringer, as all movement of the ply will have to originate there. When the back end of the ply is fixed over the transom in the middle it is time to move out from the centre, flattening each section onto the stringers as well as possible before screwing it down. The last bits to be fixed are the corners where the sheer meets the transom and the bulkhead. Screws may need to be as close together as 75 mm. in order to achieve a tight fit, and they should be staggered where possible to avoid weakening the supporting timbers.
The first section of the subdeck is laid over the transom and rear floatation compartment.
If it were not
for the fact that I have to remove this piece of subdeck
to attach the transom, I could have used staples for this part of the
job, and do it permanently in one operation. But, once the subdeck is
screwed down it can be trimmed precisely to size over the back of the
transom's inner laminations, ready to slide back into that position
once the final outer lamination is glued on, which is shown left. The
sides are left a little proud of the hull, only a few millimetres, so
that the epoxy spill and excess subdeck can be cleaned up in a single
job after the ply is glued down. That is seen below.
Now, the deck is removed and the transom piece is glued on. When it is dry the deck is replaced and the transom is trimmed to the level of the top of the decking.
The outer lamination of the transom is finally applied.
and the decking is replaced.
A few other jobs remain, apart from the outer transom strip, before the subdeck can be glued. Access ports have to be cut through bulkhead F into the floatation compartment, and that compartment has to be epoxy coated, if the decision is to do that. Also, the electric wiring to that compartment has to be led in and the position of the stern light has to be decided so that the wire can be recovered later when a hole is drilled through the deck. Finally, since the stern clam-shell vent will straddle the central deck stringer it would be useful to cut a scallop into the stringer to allow free ventilation, but I have a feeling that the back of the boat may dip into the water a bit when it is being launched from the trailer. I do not want water to flood the floatation compartment via the vent, so I shall decide on its position after the launching, when I can observe where the water comes to. I can then use a Forstner bit, or something similar, to drill out the deck hole and a bit of the stringer.
With the subdeck glued on,
the transom is trimmed down to its level.
Here, the transom is
trimmed about half way down to the subdeck level.
After trimming down to within a whisker of the subdeck and rounding the corner.
After trimming down to within a whisker of the subdeck and rounding the corner.
The transom from
behind.
This
is the point at which I will leave the transom for the time being. The
last of the trimming can be done when the covering board is ready for
fitting, so that I can adjust them both for a perfect fit without a
glue line.
Top of Page
The position of deck hardware,
such as cleats, fairleads, bollards, etc., has to be decided now,
because there will have to be hardwood backing blocks under the deck at
those locations to take the screws. These will be especially necessary
for load bearing hardware, such as mooring cleats, but not so much for
the smaller fender cleats which could probably get by with just the
thickness of the deck timbers. Nevertheless, it seem expedient to back
all hardware just in case...
The commonly seen hardware on the rear deck of slipper launches is as follows:
So, the wiring has to enter both the rudder compartment and the one astern of it, and has to pass forward via its conduit into the motor compartment, and thence to the house distribution panel, wherever that happens to be located.
The easiest equipment to acquire is 12 volt. 24 volt can be found, but not in nearly the range. If the house system is to be 12 volts, then a step down can be used from the 24 volt motor batteries, or a separate 12 volt system can be installed. In the latter case a separate recharger will be needed, either to run from the mains directly, or to tap off the motor system as it is being recharged. (In the back of my mind I am thinking that there may need to be a change to a higher voltage supply for the motor in case the planned 24 volts proves to be inadequate in this boat. It already seems to be quite heavy). If that is the case, then there will be no advantage in having a 24 volt house system, so I will go with the 12 volts.
The new LED lights used for navigation draw very little current, but let's allow a huge 5 amps, and let's tolerate a 10% voltage drop in the conductor. The distance from the distribution panel in the motor compartment to the stern nav. light is about 12.5', or 25' for the return trip. The ABYC tables show us that 18 gauge wire is suitable. Since part of the wiring will pass inside the motor compartment, the temperature rating of the conductor insulation will have to be sufficient to allow 5 amps, and the table shows that it could be as low as 140°F (or 60°C) rated. With the electric motor I expect a lot less heat than with a diesel engine, but any higher rated insulation will increase the allowed current anyway, so, provided that the insulation will withstand the heat of the motor, any one can be used with 18 gauge wire for this job.
Both lights can run off the one circuit, connected in parallel. So I need about 25' of red coated wire and 25' of black for the positive and negative conductors, or 25' of twin core.
There are other devices which will require wiring to pass down this conduit. For example, the power outlet for the fridge. The one I have draws a nominal 3 to 4 amps at 12 volts, so the same wire gauge will be alright here too. Also, the sound system speakers will be wired through the conduit, but their wiring will depend on the output of the amplifier. (The starboard speaker wiring has to run down the port side conduit, through the rudder compartment and back into the cabin again).
Electrical wiring from the motor compartment (left), into the cockpit and on to the stern.
There is a useful website converting AWG to metric sizes, http://www.engineeringtoolbox.com/awg-wire-gauge-d_731.html It shows that 18 gauge in AWG is equivalent to 0.82 mm². The smallest commonly available wire here which is multistranded, tinned copper is 1.13 mm², or AWG 17 to 16, except for speaker wire, which is 0.4 mm², or AWG 21. The 1.13 mm² will be a good general purpose wire for the domestics, and has the advantage of coming either as twin core (black and red) or twin core sheathed (in white). It comes close to $100 for 50 metres. The insulation is V90 rated PVC, which means it can tolerate 90°C (or 75°C continuously) if it is not subject to physical deformation. With those properties it can be used to carry any current load up to 20 amps, which is more than adequate for any application on the boat other than battery cables. Only an anchor windlass would draw more than 20 amps, and there is none.
Seen left is the wiring for the stern
navigation light. It is clipped up out of the way, and drip loops are
placed along its length to stop moisture running up into the
light. Its position relative to the transom will have to be measured
precisely so that a hole can be bored into the deck to retrieve the
wire when the light is attached.
Top of Page
The commonly seen hardware on the rear deck of slipper launches is as follows:
- rear-opening cowl vent
- navigation light
- ensign socket
- mooring cleat
- fairleads
- fender cleats
This is the arrangement in a
boat without a rear hatch. The 50' boats, which did have a rear hatch,
had vents in each hatch, like those in the foredeck hatches. The ensign
socket then is located astern of the hatch with the mooring cleat
forward.
In addition to that list, I am considering an electrical socket within reach of the cockpit, for the placement of a removable light on a post for night boating. Although the traditional navigation lights are very attractive they do not cast much of a warning from deck level.
Clearly, the fittings in need of the greatest strength will be the mooring cleat and fairleads. A good pair of blocks between the front end of the hatch opening and the central stringer will serve the cleat, while a couple between the sheer clamps and the outer stringers could serve the fairleads if necessary. Admittedly, if an in-line screw hole design is used, the screws from the cleat will go into the Oregon stringer, and not hardwood, but if the stringer is bolstered with blocks, and bolts are used instead of screws, the object will be achieved. Alternatively, the transverse arrangement of screws could be used, which would give the added advantage of four anchor points instead of just two.
Of these commonly available alternative designs for the mooring cleat the left and right models seem to be preferable.
I chose the left hand one because:
The backing blocks for the mooring cleat.
The position of the bolts for these blocks is determined by the need for cleat screw access.
A different arrangement is employed for the the fairleads. Not all the old boats have fairleads, but those which do locate them about half way down the length of the rear deck. They have to be as close to the sheer as practicable in order to fulfil their function, which, on the slipper launch, is to prevent the mooring line from running along the deck and chafing against the sheer. In other words, the screws from the fairleads will enter the sheer clamps, and not any blocks. To take advantage of maximum strength all that is necessary is to locate the fairleads near the junction of the sheer clamps with a bulkhead top frame. Bulkhead F happens to sit half way down the length of the rear deck, so is the perfect spot to site a fairlead. Perhaps the underneath of the sheer clamp could be reinforced with a strip of hardwood, and bolts used instead of screws, but that is probably overkill. Long screws set in epoxy or bedding compound should be perfectly adequate.
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Amongst all the many annoying stupidities of boating regulations, a stand-out example is the question of electrical wiring. In Australia the regulations are state based, not federal, which can work for or against you if you are lucky, or not. The overarching consideration in NSW is that a licensed marine electrician has to be employed for any electrical system using more than 36 volts. It implies that if you are too stupid to wire things correctly, at least you won't do too much harm as long as the voltage is low enough.
The use of metric wiring sizes here makes conversion from the AWG system (US based) necessary, if you go by ABYC recommendations. These rules seem to be the best spelled out and the clearest to use, and despite the inconvenience of having to do the conversions, it is preferable to having anything to do with the crazy bureaucratic European Union standards.
As well as wire gauges, the ABYC recommends wire colours, depending on the purpose for which they are intended. It makes good sense, as does a wiring diagram to be kept on the boat
Right now, the job is only to make provision for the navigation lights on the rear deck. Of these, one will be located astern of the hatch, overlying the empty floatation compartment between bulkhead F and the transom. The other will plug into a deck level power outlet forward of the hatch and within reach of the cockpit, so that the removable light post can be connected to it by a passenger.
Although the latter of these will be in the same general vicinity as the mooring cleat there should be no interference between them, as the light will not be used when the mooring cleat is.
In addition to that list, I am considering an electrical socket within reach of the cockpit, for the placement of a removable light on a post for night boating. Although the traditional navigation lights are very attractive they do not cast much of a warning from deck level.
Clearly, the fittings in need of the greatest strength will be the mooring cleat and fairleads. A good pair of blocks between the front end of the hatch opening and the central stringer will serve the cleat, while a couple between the sheer clamps and the outer stringers could serve the fairleads if necessary. Admittedly, if an in-line screw hole design is used, the screws from the cleat will go into the Oregon stringer, and not hardwood, but if the stringer is bolstered with blocks, and bolts are used instead of screws, the object will be achieved. Alternatively, the transverse arrangement of screws could be used, which would give the added advantage of four anchor points instead of just two.
Of these commonly available alternative designs for the mooring cleat the left and right models seem to be preferable.
I chose the left hand one because:
- It has a highly polished finish, and its 316 stainless steel looks almost like chrome.
- Its screw holes are centred transversely at 42.5 mm., which means the screws will be located in the hardwood backing blocks, and not the Oregon stringer, and
- Its height above the deck is sufficient to get a decent thickness of rope around it.
The backing blocks for the mooring cleat.
The position of the bolts for these blocks is determined by the need for cleat screw access.
A different arrangement is employed for the the fairleads. Not all the old boats have fairleads, but those which do locate them about half way down the length of the rear deck. They have to be as close to the sheer as practicable in order to fulfil their function, which, on the slipper launch, is to prevent the mooring line from running along the deck and chafing against the sheer. In other words, the screws from the fairleads will enter the sheer clamps, and not any blocks. To take advantage of maximum strength all that is necessary is to locate the fairleads near the junction of the sheer clamps with a bulkhead top frame. Bulkhead F happens to sit half way down the length of the rear deck, so is the perfect spot to site a fairlead. Perhaps the underneath of the sheer clamp could be reinforced with a strip of hardwood, and bolts used instead of screws, but that is probably overkill. Long screws set in epoxy or bedding compound should be perfectly adequate.
Top of Page
Amongst all the many annoying stupidities of boating regulations, a stand-out example is the question of electrical wiring. In Australia the regulations are state based, not federal, which can work for or against you if you are lucky, or not. The overarching consideration in NSW is that a licensed marine electrician has to be employed for any electrical system using more than 36 volts. It implies that if you are too stupid to wire things correctly, at least you won't do too much harm as long as the voltage is low enough.
The use of metric wiring sizes here makes conversion from the AWG system (US based) necessary, if you go by ABYC recommendations. These rules seem to be the best spelled out and the clearest to use, and despite the inconvenience of having to do the conversions, it is preferable to having anything to do with the crazy bureaucratic European Union standards.
As well as wire gauges, the ABYC recommends wire colours, depending on the purpose for which they are intended. It makes good sense, as does a wiring diagram to be kept on the boat
Right now, the job is only to make provision for the navigation lights on the rear deck. Of these, one will be located astern of the hatch, overlying the empty floatation compartment between bulkhead F and the transom. The other will plug into a deck level power outlet forward of the hatch and within reach of the cockpit, so that the removable light post can be connected to it by a passenger.
Although the latter of these will be in the same general vicinity as the mooring cleat there should be no interference between them, as the light will not be used when the mooring cleat is.
So, the wiring has to enter both the rudder compartment and the one astern of it, and has to pass forward via its conduit into the motor compartment, and thence to the house distribution panel, wherever that happens to be located.
The easiest equipment to acquire is 12 volt. 24 volt can be found, but not in nearly the range. If the house system is to be 12 volts, then a step down can be used from the 24 volt motor batteries, or a separate 12 volt system can be installed. In the latter case a separate recharger will be needed, either to run from the mains directly, or to tap off the motor system as it is being recharged. (In the back of my mind I am thinking that there may need to be a change to a higher voltage supply for the motor in case the planned 24 volts proves to be inadequate in this boat. It already seems to be quite heavy). If that is the case, then there will be no advantage in having a 24 volt house system, so I will go with the 12 volts.
The new LED lights used for navigation draw very little current, but let's allow a huge 5 amps, and let's tolerate a 10% voltage drop in the conductor. The distance from the distribution panel in the motor compartment to the stern nav. light is about 12.5', or 25' for the return trip. The ABYC tables show us that 18 gauge wire is suitable. Since part of the wiring will pass inside the motor compartment, the temperature rating of the conductor insulation will have to be sufficient to allow 5 amps, and the table shows that it could be as low as 140°F (or 60°C) rated. With the electric motor I expect a lot less heat than with a diesel engine, but any higher rated insulation will increase the allowed current anyway, so, provided that the insulation will withstand the heat of the motor, any one can be used with 18 gauge wire for this job.
Both lights can run off the one circuit, connected in parallel. So I need about 25' of red coated wire and 25' of black for the positive and negative conductors, or 25' of twin core.
There are other devices which will require wiring to pass down this conduit. For example, the power outlet for the fridge. The one I have draws a nominal 3 to 4 amps at 12 volts, so the same wire gauge will be alright here too. Also, the sound system speakers will be wired through the conduit, but their wiring will depend on the output of the amplifier. (The starboard speaker wiring has to run down the port side conduit, through the rudder compartment and back into the cabin again).
Electrical wiring from the motor compartment (left), into the cockpit and on to the stern.
There is a useful website converting AWG to metric sizes, http://www.engineeringtoolbox.com/awg-wire-gauge-d_731.html It shows that 18 gauge in AWG is equivalent to 0.82 mm². The smallest commonly available wire here which is multistranded, tinned copper is 1.13 mm², or AWG 17 to 16, except for speaker wire, which is 0.4 mm², or AWG 21. The 1.13 mm² will be a good general purpose wire for the domestics, and has the advantage of coming either as twin core (black and red) or twin core sheathed (in white). It comes close to $100 for 50 metres. The insulation is V90 rated PVC, which means it can tolerate 90°C (or 75°C continuously) if it is not subject to physical deformation. With those properties it can be used to carry any current load up to 20 amps, which is more than adequate for any application on the boat other than battery cables. Only an anchor windlass would draw more than 20 amps, and there is none.
Seen left is the wiring for the stern
navigation light. It is clipped up out of the way, and drip loops are
placed along its length to stop moisture running up into the
light. Its position relative to the transom will have to be measured
precisely so that a hole can be bored into the deck to retrieve the
wire when the light is attached.Top of Page
64. Laying the Rear Sub Deck
Prior to the advent of epoxy
there could have been a real problem with the decking in this boat. It
used to be said that segments in a ply deck should not terminate at the
corner of an opening, such as a hatch or a cockpit. That would allow
weaknesses in the structure. The rule has been relaxed because of
epoxy. Had that not been the case the rear deck segment would have had
to reach from the transom to bulkhead D in the middle of the cockpit
area, in order to avoid a corner: forward of the transom the first
bulkhead reached is bulkhead F, and that has the stern corners of the
rear deck hatch next to it. Forward of that the next bulkhead reached
is bulkhead E, which is the rear extremity of the cockpit. Bulkhead D
would be suitable, but the distance from the transom to bulkhead D is
too great for a single sheet of ply.
On the front deck things are not quite so tight: the hatch rides on bulkhead B, but the dash bulkhead (C) is free of both hatch corners, and (since the redesign of the windscreen area) of cockpit corners as well. Mind you, prior to the redesign the same problem would have pertained.
But, as I say, it is no longer imperative to avoid corner terminations, so on the rear deck the segments can be as follows:
On the front deck things are not quite so tight: the hatch rides on bulkhead B, but the dash bulkhead (C) is free of both hatch corners, and (since the redesign of the windscreen area) of cockpit corners as well. Mind you, prior to the redesign the same problem would have pertained.
But, as I say, it is no longer imperative to avoid corner terminations, so on the rear deck the segments can be as follows:
- A piece to cover the area between the
transom and bulkhead F.
- A piece for the port half over the area between bulkhead F and bulkhead D, with a cutout for the hatch, and
- A similar one for the starboard half.
Anyway, the immediate need is to clean up the sheer clamps, which until now have been left pretty much as they first emerged from their glue-up, covered in squeezed-out epoxy, and not precisely flush with the hull sides. The epoxy is now planed away and the hull and sheer lined up exactly, with care to check with a batten for conformity with the camber. In some areas there may be slight dips or gaps which do not close, but they will be filled with epoxy bog. The junction of deck with hull is going to be covered with a rubbing strake later anyway, so a little epoxy filled gap here is no problem. The important thing is to achieve a good flowing line for the decking.
Before and after cleaning up the sheer clamp.
Now is the time to decide whether to paint everything with epoxy or to leave it exposed. There are arguments for both. But once the subdeck is on it is too late to change your mind. I decided to epoxy coat everything, starting in the floatation compartment.
Epoxy coating in the floatation compartment. Note the ventilation hole to the transom and the limber holes to the
rudder compartment.
Just before gluing down the
deck, I suddenly remembered the rubbing strakes on the outside of the
hull. The lower one of these will have nothing but the hull itself to
screw into. (The upper one has the sheer clamps). From the accessible
compartments the screws can be put in from inside, but in the
floatation compartment that will not be possible, so I added two lines
of blocking inside the hull for the screws from the outside to bite
into
later.The same will have to be done in the forward compartments
too.
The backing strip
for the starboard lower rubbing strake is glued to the inside of the
hull.
Finally, we are ready for the subdeck. Using the screw holes which were established when the deck was temporarily laid for the trimming of the transom, the subdeck segment from transom to bulkhead F is now permanently laid, this time over generous columns of thickened epoxy running over the sheer, the bulkhead top frames, the transom and the deck stringers. The piece is screwed down again, but the screws are waxed to discourage bonding, as they will be removed when the glue has set up.
The forward end of this subdeck piece is angled to continue the line of the hatch opening, and it comes as far forward as the hatch itself at the bulkhead F level, but lateral to the hatch it is cut back a little to reveal about half of the thickness of the bulkhead top frame, because the next bit of subdeck has to land on the frame as well.
The distance
from
bulkhead F to bulkhead D is over
2.5 metres, so a single piece of ply cannot be used. Instead, I have
used a narrow strip from bulkhead E to D, bridging the gap between the
sheer and the carling. Forward of bulkhead D it becomes a bit more
complicated because of the re-design of the windscreen. Instead of
running up to the dash bulkhead (C) as a narrow strip it has to widen
to fill in the gap between the screen and the dash bulkhead as well.
So, I will leave that until after the stern is finished.
Every now and again you encounter a dip in the sheer clamps which would result in an untrue deck camber or slope if left uncorrected. A shim can be added there and planed down to a true line, and any resulting gaps can sunbsequently be filled with epoxy when the subdeck is being applied.
A shim raises a slight dip in the sheer at the level of bulkhead E.
At the end of the month only the sternmost section of the subdeck is glued down. The remainder, up to bulkhead E, can now be added, and the hatch can be covered. These tasks will be interspersed amongst the jobs for December, which are going to take me back to the forward compartments.
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Problems shows higher resolution shots as well.