| T.R | Title | User | Personal
Name | Date | Lines |
|---|
| 292.1 | Clarify ? | GRAMPS::WCLARK | Walt Clark | Tue Apr 29 1986 09:59 | 4 |
| Does the thru hull have a flush mount or surface mount flange ?
Walt
|
| 292.2 | More on Signet Transducers | OBLIO::MCWILLIAMS | | Tue Apr 29 1986 11:03 | 35 |
| I was looking into also using a Signet MK267 Knot/Log and the
transducer looks something like this:
+-------+ -
| | |
| | |
| | | 2.68"
| | |
| | |
_/ \_ |
/ \ |
------------- -
|------------|
2.50"
It is designed to flush mount. The mounting instruction call for the
use of their MK 15.8 cutter, which cuts the hole, and 45 degree bevel
in one cut. The cost of the cutter is $80 list, and nobody seems to
carry it. Also included are instructions on how to use a 45 degree
bevel cutter and a standard hole cutter.
I happen to already have a hull pipe installed and am looking to see
if I can modify the tranducer (spelled grinding off the flange) and
get it to fit the hull pipe. The advantage of the hull pipe is the
ability to remove the tranducer to unfoul it while only taking on
a gallon or two of water (the hull pipe comes with a cap).
It seems all of Signet's instruments (depth & Log) come with this
flush mount type of transducer (probably inspired by the racing set).
I wish you luck.
/jim
|
| 292.3 | Mounting block?? | SUMMIT::THOMAS | Ed Thomas | Tue Apr 29 1986 12:44 | 9 |
| Isn't he going to have to put a block in to get the transducer pointing
directly towards the bottom? (assuming that he doesn't have a flat
bottom boat!!) And if that's the case, won't the bevel be cut into
the block which could be done with a sabre saw or router.
I must be missing something!!
Ed
|
| 292.4 | one way to do it | PULSAR::BERENS | Alan Berens | Tue Apr 29 1986 13:14 | 49 |
|
+-------+ -
| | |
| | |
| | | 2.68"
| | |
| | |
_/ \_ |
/ \ |
------------- -
|------------|
2.50"
Yes indeed, the Signet design requires a hard to make hole. With a
little creativity, you can get along without Signet's tool. Buy two good
holes saws -- 2.5" and 1.625" (I think -- check Signet's drawing). Drill
the 1/4" pilot hole for the hole saw. Using the 2.5" hole saw make a
3/8" deep cut. Now cut all the way through with the smaller hole saw.
Now carefully cut away the fiberglass between the small through hole and
the 3/8" deep cut with the larger hole saw. Use a sharp chisel. (Note: if
your hull is less than 3/8" thick, you have another problem.) You now
have a nice, straight-sided, flat-bottomed recess in the hull. The
transducer through-hull should be flush with the hull. Now you can
forget about bevel and simply install the through-hull with lots of
bedding compound. Don't forget to use a plywood backing plate
(preferably epoxy sealed) inside the hull. If you want to worry about
the bevel (ie, you have too much spare time and how would you like to
help me paint my bottom?), get out your epoxy and fillers, make a peanut
butter-like paste, and spread some around the corner of the hole in the
hull. Coat the through hull with something the epoxy won't stick to
(eg, several coats of paste wax) and shove it into the hole. Let the
epoxy harden. You now have a nice beveled hole. Warning: You definitely
risk gluing the through-hull into the hull this way. Wrap a couple of
layers of plastic sheet around the threaded stem of the through hull.
Even if the epoxy doesn't stick, it will form threads around the
through-hull threads. Remove the through-hull as soon as the epoxy
becomes firm. Now figure out how to clean the wax off the through-hull
so the bedding compound will stick.
Another warning: Signet's prices for spare parts are quite high. My
windspeed transducer seized. I stupidly paid Signet $140 for a new one.
I later replaced the bearings in the original transducer for $12 with
standard, over the counter bearing from the local bearing house. Now I
have a spare transducer. I'd rather have $128.
Good luck.
|
| 292.5 | On transducer Placement | OBLIO::MCWILLIAMS | | Tue Apr 29 1986 13:36 | 29 |
| Re: .3
> Isn't he going to have to put a block in to get the transducer pointing
> directly towards the bottom? (assuming that he doesn't have a flat
> bottom boat!!) And if that's the case, won't the bevel be cut into
> the block which could be done with a sabre saw or router.
The Knot Log come with a setable compensation to account for
placement. The Depth Sounder has a 112 degree cone pattern and it
picks up the first "solid" echo as the depth. Placement of the
piezoelectric tranducer is therefore less critical. The only
advice they give is to mount it far enough from the keel so that
you don't get echos off the keel. The Depth instrument also comes
with a setable Keel offset.
One other idea for a depth sounder is to mount it in mineral oil
filled chamber inside of the hull. The advantages are one less hole
in the hull and less chance of barnacle growth on the face of the
transducer (BTW they recommend that you use a special anti-fouling
paint on the face of the depth sounder transducer), the disadvantages
are lower outgoing signal strength and lower sensitivity of returns.
Generally this results in "iffy" reading for depths greater than
20-25 fathoms, however, if your main use is for making sure you
don't run aground, it works just great in shallow waters. If you
use the depth sounder for navigation or following depth contours
offshore, this solution probably isn't for you.
/jim
|
| 292.6 | Solution ???? | BPOV09::TMOORE | | Tue Apr 29 1986 13:47 | 25 |
| Thanks for the help, one suggestion I received (not through the
notes file) was the following
+---------+ +--------+
| hull | hole in | hull |
| | the hull | |
+---------+ +--------+
+--------+ +--------+
| / \ |
|wood / \ wood |
+------+ +------+
The wooden piece would be made of oak and turned on a lathe. Some
sort of bedlast (boat life ect.) would be placed between the hull
and wood plus in the hole.
Comments please, can anyone see why this would not work??
Tom
|
| 292.7 | maybe | PULSAR::BERENS | Alan Berens | Tue Apr 29 1986 14:16 | 9 |
| I used a beveled mahogany block in a similar manner to get my depth
sounder transducer pointing straight down. I sealed the mahogany with
epoxy and six years later all is well. However, it rather defeats the
purpose of a flush mounting. More importantly, the block may create enough
turbulence to cause erratic knotmeter or log readings. The little
paddlewheel likes nice even water flow past it. I would be reluctant to
try this scheme for a knotmeter.
|
| 292.8 | donuts again | GRAMPS::WCLARK | Walt Clark | Tue Apr 29 1986 14:20 | 18 |
| I have tried the inside the hull mounting (both in mineral oil bubble
and silicone rubber potted) and been very disapointed in performance.
More false alarms than Chicken Little.
I mounted the transducer on my last boat on a vertical fairing made
of Marinetex because the forward Vee was pretty radical. My current
boat allowed mounting my Datamarine transducer about 15 degrees
off vertical. I have never had a problem with loss of the bottom
on a starboard tack where the transducer can be angled away from
the bottom as much as 45 degrees.
Your last idea leaves me with a concern about the strength of the
donut (yes, we are back to donuts again) outside the hull made
from a single piece of wood. I would be more comfortable if this
were made of something bullet proof like Marinetex though.
Walt
|
| 292.9 | special tools needed? | ADS::MACKINNON | | Wed Apr 30 1986 12:52 | 14 |
| I don't think anybody answered your original question. Arey's marina
purchased the special cutter from signet(it is expensive). They
do enough instalations to merit having the tool. I would imagine
any marina catering to signet instrument would also have the tool.
My signet was installed by Don Peacock who is now with Seabrook
Marine. He did the job without the tool(it took about twice as long)
and it turned out excellant this will be our fourth season and no
problems have occured. So, there it is, you can do it either way,
but without the tool you should be a bit of a craftman
Arey's Marina is located of route 109 in Moultonboro N.H. on
Lake Winnipesaukee.
good luck
Don
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