Fixing transducers to alluminium ?

[Billo]

Guys , just looking for the best way to fix the transducer to an aluminium boat ...

I have been told to get ' monel '(*spelling ?? ) screws ? never heard of em !

can anyone else give me advise on the best ways to fix transducers / sounders / leads etc to the boat ?? know certain metals react with the aluminium , so any advice on the safest and easiest way to do it appreciated

[MarcusD]

I've never heard of those screws... I just used stainless screws, but my boat is ancient and a bit more corrosion isn't going to matter.

So when did you pick up the boat?

Let me know if you need a hand with wiring it up - I've got the next few days off.

[peterbo3]

Hi Billo,
Monel refers to a rivet type that is compatable with alum. You can use SS fasteners with Lanoline based anti-corrosion coatings.

[Billo]

cheers fellas ...
just want to make sure i got it right first time !!!
Better do a trip to the hardware [smiley=2thumbsup.gif]

Marcus , picked it up last night ..
I am gonna go for a run tomorrow if your interested on coming for a spin with me ....maiden voyage !

[MarcusD]

I think I promised to take the Mrs shopping..... I'll see if I can get out of it. I'll let you know tonight.

[whiteman]

BIAS sells small tubes of "anti-corrosive jointing paste" for $28.95. Too much for me. I'll stick to Lanotec.

[Billo]

Would aluminium pop rivets do the job ?

[MarcusD]

Can't see why aluminium ones wouldn't do the job.

[Big_Kev]

Nooooooooooooo!

[CHRIS_aka_GWH]

kev's spot on - unless you intend using the transducer as skip bait / part of a teaser spread.

the consant pressure on the rivets will collapse them - they are only aluminium after all - rivets were never designed for tensile strength.

Even using a sacrifical metal such as plain steel would be more desirable. Personally I used marine grade s/s self tapers absolutely covered in sikaflex in a 12footer for 5yrs with no sign of metal rot.

chris
chris

[MarcusD]

lol bad advice from me then

How did the maiden voyage go?

[Kerry]

Monel is a basically a copper-nickel alloy and with around 28% copper then you decide you you want to fix then into alloy ???

Stainless is basically a chromium-nickel alloy and more resistent to corrosion than monel, be they nails, screws, bolts or whatever.

If the transducer bracket is SS then one certainly doesn't need to introduce another metal type let alone one that sits with the bronzes, copper and brasses as far as galvanic corrosion is concerned.

As for SS self tapers, well some transom's don't have enough meat to grip half a thread let alone hold much.

Many alloy boat builders fit external alloy brackets for mounting transducers etc and nothing quite beats a (SS) bolt and nyloc to keep things in place.

As for alloy rivets? don't really count these out either especially if they are the correct size etc as the next time you fly, take a peak out the window, thats about all that holds planes together

The one thing will alloy rivets is to ensure they are ALL alloy (and closed) and not simply an alloy head with a steel mandrel, nothing worse on the boat than an alloy rivet with a piece of cheap steel stuck in the middle.

Cheers, Kerry.

[CHRIS_aka_GWH]

good points kerry

but, there is a signifigant degree of torsion (lever action) involved on a sounder probe as oppossed to the aerodynamic pressure forces on an aircrafts skin (which incidently is held at thousands of points).

i seriously wouldn't use rivets, galvanic action aside (& kerry makes a good point about stainless already being in the equation) on the most basic level they are not adjustable & if they loosen in the slightest ???

chris

ps the transom of the 12 footers was sandwiched with some 4mm aluminium angle on the inside - it was a much better set up & gave excellent sounding at high speed than the ventilation problems I encounter sometimes with a poorly concieved Telwater sounder bracket

[Kerry]

I probably wouldn't use rivits either but when comparing say miserable little self tapers into a single skin then one must weigh up the practical side and in this type of situation I wouldn't use either.

I also wouldn't be too keen to self tap through the transom skin then into internal bracing? but would depend a little on the structural design.

Even an external welded bracket has to be done right the first time to ensure the best water flow, less disturbance etc.

Cheers, Kerry.

[NeilD]

One option to think about when setting up is sticking it on with Sikaflex. I had one on an old Abalone for six years. I only stuck it on temporarily to check the placement and it stayed there.

Cheers Neil