seasponge Posted January 29, 2018 Share Posted January 29, 2018 I’m relatively new to boating and bought an old second hand aluminium boat a couple of years ago. I am slowly learning all the boats do’s and don’ts, both on and off the water. What is the practice for using screws/fixings into aluminium hull. I’m assuming 316 stainless steel, but then what about the use of dissimilar metals? I’m looking at two scenarios; outside boat below water (ie to mount a transducer bracket), and inside boat above water (ie to mount rod holders to inside back of boat and cup holders and fish finder display to dashboard). Link to comment Share on other sites More sharing options...
PaddyT Posted January 29, 2018 Share Posted January 29, 2018 Duralac on everything- dont forget even having two different grades of aluminium will potentially cause dissimilar metal corrosion. Nylon sleeves on fittings can be a help too- but its bloody hard to completely overcome. Link to comment Share on other sites More sharing options...
raging Posted January 29, 2018 Share Posted January 29, 2018 Probably the same thing but I use tef-gel Link to comment Share on other sites More sharing options...
Berleyguts Posted January 29, 2018 Share Posted January 29, 2018 For the transducer bracket, why not consider getting someone to weld on a mount for you? Saves drilling holes through your transom so close to the waterline. Link to comment Share on other sites More sharing options...
Welster Posted January 29, 2018 Share Posted January 29, 2018 (edited) It’s hard to know what’s the best way. We use Tefgel as above as one option. Fittings like rod holders we drill the appropriate size rivet holes and prime and paint them. We use sikkafkex under the rod holders to seal them, rivet them down and clean off any excess. Other fittings we have drilled over size holes primed and painted. We used nylon fixings with sikka or tefgel on and around the hole. We avoid self tapping screws as much as possible. They break the paint moisture gets under it, the aluminium oxidises and the bubbles grow from there. That’s my take on it anyway. To us it’s all about stopping moisture and salt getting near raw aluminium at the fixing point. It’s a bit of mucking around. Another thing we have done is wax the top deck off the boat trying to prevent any minute imperfections in the paint allowing moisture through. That makes it slippery though. I hope that helps. Good luck. Edited January 29, 2018 by Welster Typo 1 Link to comment Share on other sites More sharing options...
rickmarlin62 Posted January 29, 2018 Share Posted January 29, 2018 I amostly used rivets..end rivets so no water intrudes..if not 316 s/s bolts oversize holes sikaflex or heat shrink...rick Link to comment Share on other sites More sharing options...
Guest Guest123456789 Posted January 29, 2018 Share Posted January 29, 2018 For the transducer mount I used an Old ice cream container to make plastic washers. Perfect material, helps with watertight seal and eliminates electrical interference or risk of a reaction to the metal. Plus it cost $0 Link to comment Share on other sites More sharing options...
Berleyguts Posted January 29, 2018 Share Posted January 29, 2018 38 minutes ago, flatheadluke said: For the transducer mount I used an Old ice cream container to make plastic washers. Perfect material, helps with watertight seal and eliminates electrical interference or risk of a reaction to the metal. Plus it cost $0 And it’s an excuse to eat more ice cream. ?? Link to comment Share on other sites More sharing options...
Guest Guest123456789 Posted January 29, 2018 Share Posted January 29, 2018 26 minutes ago, Berleyguts said: And it’s an excuse to eat more ice cream. ?? Does make it harder to get up on the plane though ? Link to comment Share on other sites More sharing options...
seasponge Posted January 29, 2018 Author Share Posted January 29, 2018 Thanks for all the replies. It appears i'd underestimated the issue. I havent put any fixings in yet, but was about to. None of the videos i watched about transducer installation mentioned anything about treating the screws or holes. Although, it appears the previous owner or (owners) weren't too concerned. There's fixings everywhere and i havent seen any sign of any duralac or tef-gel (man, that stuff is expensive by the way). The boat is old, and there's signs of corrosion at the transom. Rick, for rivets, do you coat them in anything prior to installation? Link to comment Share on other sites More sharing options...
Berleyguts Posted January 29, 2018 Share Posted January 29, 2018 29 minutes ago, seasponge said: Although, it appears the previous owner or (owners) weren't too concerned. There's fixings everywhere and i havent seen any sign of any duralac or tef-gel (man, that stuff is expensive by the way). You don’t need a lot of Duralac. It goes a long way. ? I just dip the screws into the nozzle of the tube and the screw or bolt is coated. I just changed rod holders over from riveted plastic ones to s/s with a gasket and s/s bolts and lock nuts and my tube of Duralac had been sitting in the garage at my old place for a few years and I’ve been in Port for 10 months. I keep a bit of gaffer tape around the cap to keep air out. Link to comment Share on other sites More sharing options...
rickmarlin62 Posted January 30, 2018 Share Posted January 30, 2018 just a smear of sikaflex it works on everything haha Link to comment Share on other sites More sharing options...
seasponge Posted January 30, 2018 Author Share Posted January 30, 2018 On 30/01/2018 at 8:31 AM, Berleyguts said: You don’t need a lot of Duralac. It goes a long way. 18 hours ago, rickmarlin62 said: just a smear of sikaflex it works on everything haha I think i'll try to go sealed rivets wherever practical, with plenty of Duralac or similar. Are aluminum sealed/closed rivets readily available. I tried the major hardware store, but they didn't have sealed rivets. Link to comment Share on other sites More sharing options...
rickmarlin62 Posted January 30, 2018 Share Posted January 30, 2018 if bunnings don't have them try a metaland agent Link to comment Share on other sites More sharing options...
Berleyguts Posted January 31, 2018 Share Posted January 31, 2018 Or your local chandlery. Link to comment Share on other sites More sharing options...
Welster Posted January 31, 2018 Share Posted January 31, 2018 They might call them cherry blind rivets. Link to comment Share on other sites More sharing options...
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