Reply
 
Thread Tools Search this Thread
 
Old 11 January 2012, 09:02   #1
Member
 
Country: UK - Scotland
Boat name: Wildheart
Make: Humber/Delta Seasafe
Length: 5m +
Engine: Merc 60 Clamshell
MMSI: 235068449
Join Date: Apr 2007
Posts: 4,667
How smooth does a sounder bottom need to be?

Busy fityting my new (to me) toy, which came with a transom mount depth transducer.

Said transducer had been fitted internally to the previous owner's boat, so I have spent a couuple of evenings carefully chiselling off the epoxy that held it in. It's now back to plastic but with one tiny groove on the bottom face caused by the chisel when I probably should have stopped chipping & gone to bed 10 mins before.....

So, the question - knowing it has to work in as smooth water flow as possible, should I be sanding this "deep scratch" out the plastic, or are they robust enough to handle that kind of damage? I assume some must have worse from being grounded? (scratch is about 4mm long and about 0.25mm deep)

Also can anyone tell me how smooth the surface is on a "fresh" one? (or do I need to polish it - or will a careful circular sanding with an old rag & 1200 grade wet'n'dry be sufficient?
__________________
9D280 is offline   Reply With Quote
Old 11 January 2012, 09:07   #2
Member
 
Country: UK - England
Town: Gloucestershire
Boat name: Osprey
Make: Osprey Vipermax
Length: 5m +
Engine: E-tec 300 G2
MMSI: TBC
Join Date: Dec 2006
Posts: 4,020
I would use some epoxy to fill the scratch then sand it smooth.
__________________
---------------------------------------------------
Chris Stevens

Born fiddler
Chris is offline   Reply With Quote
Old 11 January 2012, 10:21   #3
Member
 
Country: UK - England
Town: Northampton
Make: RibTec
Length: 5m +
Engine: Outbaord mariner 75
Join Date: Apr 2011
Posts: 506
yep Fill in the scratches with epoxy and epoxy it to the outer hull to shoot through.
I have had on in my sump for years.
Had to change the transducer a few times and never had any issues.
make sure the epoxy is fairly bubble free and your away.

But geneerally its not too important. as the sound wave should not be too much effected by the state of the transducer. the odd scratch should be fine.
__________________
jezza2011 is offline   Reply With Quote
Old 11 January 2012, 10:25   #4
Member
 
Erin's Avatar
 
Country: UK - Channel Islands
Town: A large rock
Boat name: La Frette
Make: Osprey Vipermax
Length: 6m +
Engine: 200 Suzzy
Join Date: May 2004
Posts: 2,893
I really doubt a scratch/groove will cause a problem. If you consider that they are often mounted in hull firing though fibreglass and antifoul I'm sure you'll be fine.
Erin is offline   Reply With Quote
Old 11 January 2012, 10:48   #5
RIBnet admin team
 
Poly's Avatar
 
Country: UK - Scotland
Boat name: imposter
Make: FunYak
Length: 3m +
Engine: Tohatsu 30HP
MMSI: 235089819
Join Date: Sep 2005
Posts: 11,622
Its detecting changes in "density" of the material, on the back of the boat I wouldn't expect a problem its going from plastic to water and it won't have the resolution to "see" a 4x0.25mm feature - unless it doesn't wet properly - because the groove is too thin - then it will effectively be trapping an air bubble and might not be so happy.

Likewise if you decide to mount it in the sump and silicone/epoxy it in place you want to be sure you aren't getting a bubble in your "ding".
__________________
Poly is offline   Reply With Quote
Old 11 January 2012, 11:10   #6
Member
 
Country: UK - Scotland
Boat name: Wildheart
Make: Humber/Delta Seasafe
Length: 5m +
Engine: Merc 60 Clamshell
MMSI: 235068449
Join Date: Apr 2007
Posts: 4,667
Thanks guys.

Sump - I wish! This is going to have to be transom mounted.

Pol has hit the nail on the head - the air / vcaccum bubble it might create at 20+ odd knots was my concern. I guess if it tells me obvious rubbish at speed it's a wide angle transducer so I could probably angle it ever so slightly down at the rear to try & up the fluid pressure on the bottom face a bit & reduce the likelihood of that happening.

In the meantime I'll sand it a bit smoother & see what happens... as I motor off into the sunset thinking Jaws is hot on my tail
__________________
9D280 is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off




All times are GMT. The time now is 11:48.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.