Reply
 
Thread Tools Display Modes
 
Old 03-27-2015, 09:19 PM   #1
Guru
 
healhustler's Avatar
 
City: Longboat Key, FL
Country: USA
Vessel Name: Bucky
Vessel Model: Krogen Manatee 36 North Sea
Join Date: Oct 2009
Posts: 4,178
SS screws in alum frame window?

I'm in the middle of installing larger Krogen 48 salon windows in my Manatee 36. After speaking to Krogen about any possible stress risks, I am moving forward on the project but since these windows are stronger, thicker , screw-fastened alum framed instead of the original plastic glue-in jobs, the usual SS screws I use for most things may not be appropriate against the aluminum. Should I look for alum screws or just dab the holes with some Algrip primer or something? Thanks in advance.
__________________
Advertisement

__________________
Larry

"I'd rather be happy than dignified".
healhustler is offline   Reply With Quote
Old 03-27-2015, 09:33 PM   #2
Guru
 
N4712's Avatar
 
City: South FL
Country: U.S.A
Vessel Name: Oliver
Vessel Model: Nordhavn 47 Hull# 12
Join Date: Apr 2013
Posts: 3,613
Quote:
Originally Posted by healhustler View Post
I'm in the middle of installing larger Krogen 48 salon windows in my Manatee 36. After speaking to Krogen about any possible stress risks, I am moving forward on the project but since these windows are stronger, thicker , screw-fastened alum framed instead of the original plastic glue-in jobs, the usual SS screws I use for most things may not be appropriate against the aluminum. Should I look for alum screws or just dab the holes with some Algrip primer or something? Thanks in advance.

Liberally apply Tef-Gel and use nylon washers.
__________________

__________________
Thanks, Oliver
M/V Oliver
Nordhavn 47 Hull #12
N4712 is offline   Reply With Quote
Old 03-27-2015, 10:29 PM   #3
Scraping Paint
 
City: -
Country: -
Join Date: Oct 2007
Posts: 13,748
Stainless steel and aluminum are quite aways apart on the galvanic chart.

I was told of a case where a floatplane owner decided to replace a lot of the galvanized fasteners in the plane's float system with stainless fasteners thinking they would hold up in the saltwater environment he flew in better than the galvanized fasteners which would start to rust as the galvanizing went away.

The result was severe corrosion in the structural aluminum around the stainless fasteners and a serioulsy massive repair bill.

When we changed our PNW boat's old Raytheon rader to a new Furuno radar some years ago, we had PYI fabricate a short pylon for the antenna to sit on to center it over the existing mount. The pylon is powder-coated aluminum. The mount is stainless steel as were the bolts, nuts, and washers PYI gave us to attach the pylon to the mount. They gave us nylon inserts and washers to isolate the mounting hardware from the aluminum pylon base. Otherwise, the pylon base would have been attacked by corrosion around the stainless mounting bolts and washers.
Marin is offline   Reply With Quote
Old 03-27-2015, 10:50 PM   #4
Guru
 
LarryM's Avatar
 
City: League City, TX
Country: USA
Vessel Name: Pelago
Vessel Model: Wellcraft 3300 Coastal
Join Date: Aug 2011
Posts: 843
Another vote for Tef-Gel. I have used it for years on sailboat masts and rigging where stainless steel fittings are routinely attached to aluminum spars. This compound is also widely used by shipbuilders and marine specialists.
__________________
Larry
M/V Pelago
LarryM is online now   Reply With Quote
Old 03-27-2015, 11:09 PM   #5
Senior Member
 
Martin J's Avatar
 
City: Mt Crested Butte
Country: USA
Vessel Name: St Christopher
Vessel Model: Cheoy Lee 50ft tri-cabin
Join Date: Feb 2013
Posts: 243
There is a quite amazing compound called Tefgel a modified ptfe paste. Expensive but good stops corrosion in dissimalar metals , stainless galling and lubricates as a anti sieze. You should check it out
Martin J is offline   Reply With Quote
Old 03-28-2015, 08:12 AM   #6
FF
Guru
 
FF's Avatar
 
Join Date: Oct 2007
Posts: 16,515
I have used plumbers tefflon tape with good results.

Sure it will stick a bit , but its fast , easy and the stuff is in your toolbox now.

Otherwise as suggested triple dip (not flash galv) bolts will work .
FF is offline   Reply With Quote
Old 03-28-2015, 09:00 AM   #7
TF Site Team
 
Larry M's Avatar
 
City: JAX, FL
Country: USA
Vessel Name: Hobo
Vessel Model: Krogen 42-120
Join Date: Nov 2008
Posts: 5,725
I've been using Duralac with good results. We were introduced to it when we were in NZ. Duralac is used extensively by spar manufacturers when attaching SS hardware. It was was originally developed for the airline industry.


http://www.llewellyn-ryland.co.uk/downloads/duralac.pdf
Attached Thumbnails
Click image for larger version

Name:	016.jpg
Views:	62
Size:	139.5 KB
ID:	38639  
Larry M is online now   Reply With Quote
Old 03-28-2015, 09:22 AM   #8
Guru
 
Capt.Bill11's Avatar
 
City: Sarasota/Ft. Lauderdale
Country: USA
Join Date: Apr 2014
Posts: 5,422
Tef-Gel is standard kit on aluminum vessels where SS fasteners are used all the time.
Capt.Bill11 is offline   Reply With Quote
Old 03-28-2015, 11:04 AM   #9
Guru
 
Nomad Willy's Avatar
 
City: Concrete Washington State
Country: USA
Vessel Name: Willy
Vessel Model: Willard Nomad 30'
Join Date: Oct 2007
Posts: 13,707
I'm not an electrolysis expert but I'll bet brass is much closer to aluminum on the scale. I just used 32 #10 X 1 1/2 brass screws on a platform I'm building in my stern cockpit and was amazed at the $.55 each cost. Must be because of the copper content of brass. I know they aren't as strong but when I decided on brass I doubled the number of screws.

And I know brass looses it's "bright" appearence quickly.
__________________
Eric

North Western Washington State USA
Nomad Willy is offline   Reply With Quote
Old 03-28-2015, 12:54 PM   #10
Guru
 
Capt.Bill11's Avatar
 
City: Sarasota/Ft. Lauderdale
Country: USA
Join Date: Apr 2014
Posts: 5,422
Copper, salt water and aluminum can be a bad combination.
Capt.Bill11 is offline   Reply With Quote
Old 03-28-2015, 01:18 PM   #11
Guru
 
caltexflanc's Avatar
 
City: North Carolina for now
Country: USA
Vessel Name: Small Incentive
Vessel Model: Boston Whaler 130 Sport
Join Date: Aug 2011
Posts: 3,785
Brass and and aluminum and salt water... nope, not a good idea, will need Tef gel just like stainless.
__________________
George

"There's the Right Way, the Wrong Way, and what some guy says he's gotten away with"
caltexflanc is online now   Reply With Quote
Old 04-02-2015, 12:14 PM   #12
Senior Member
 
Old deckhand's Avatar
 
City: Sitka
Country: Same
Vessel Model: Transpacific Marine Eagle 32
Join Date: Dec 2014
Posts: 497
Agree, Tef Gel works. Having owned several aluminum boats and have noted that the manufactures recommend only stainless fasteners.
Old deckhand is offline   Reply With Quote
Old 04-02-2015, 01:21 PM   #13
Guru
 
Nomad Willy's Avatar
 
City: Concrete Washington State
Country: USA
Vessel Name: Willy
Vessel Model: Willard Nomad 30'
Join Date: Oct 2007
Posts: 13,707
Thanks guys .. that's what I needed to know.

Old Deck,
Yes I remember a friend in Thorne Bay that has a Hewes Craft 18 and they attached stuff w SS fasteners. And there was considerable corrosion right next to the SS. ??

I just used some brass screws in a wood bench (small) in my aft cockpit. Got me thinking about it.
__________________
Eric

North Western Washington State USA
Nomad Willy is offline   Reply With Quote
Old 04-02-2015, 07:17 PM   #14
Guru
 
BruceK's Avatar
 
Join Date: Oct 2011
Posts: 7,561
Duralac is used here. Colloquially called "cocky shit" for its similarity in appearance and consistency to bird droppings, messy to use.
Would monel screws overcome the problem? Never heard of aluminum screws, ? too soft.
__________________
BruceK
Island Gypsy 36 Europa "Doriana"
Sydney Australia
BruceK is offline   Reply With Quote
Old 04-02-2015, 07:31 PM   #15
Senior Member
 
Vashon_Trawler's Avatar
 
City: St. Petersburg, Florida
Country: USA
Vessel Name: M/V Sherpa
Vessel Model: 24' Vashon Diesel Cruiser
Join Date: Jun 2013
Posts: 426
This thread has me confused... What else would we use but SS steel screws? Aluminum screws? Too soft as a poster noted. I have an aluminum ham radio tower and the factory secured each section with SS screws--been up there for years and no signs of corrosion although I do use anti-seize compound. All my windows in Sherpa use SS screws--no signs of corrosion/electrolysis.
__________________
“Go small, go simple, go now”
― Larry Pardey, Cruising in Seraffyn
Vashon_Trawler is offline   Reply With Quote
Old 04-02-2015, 08:26 PM   #16
Senior Member
 
Old deckhand's Avatar
 
City: Sitka
Country: Same
Vessel Model: Transpacific Marine Eagle 32
Join Date: Dec 2014
Posts: 497
Quote:
Originally Posted by manyboats View Post
Thanks guys .. that's what I needed to know.

Old Deck,
Yes I remember a friend in Thorne Bay that has a Hewes Craft 18 and they attached stuff w SS fasteners. And there was considerable corrosion right next to the SS. ??

I just used some brass screws in a wood bench (small) in my aft cockpit. Got me thinking about it.
Eric,

I wonder about the quality of the stainless they used. Many of us have using stainless for years without a problem.

Ken
Old deckhand is offline   Reply With Quote
Old 04-02-2015, 09:45 PM   #17
Guru
 
Nomad Willy's Avatar
 
City: Concrete Washington State
Country: USA
Vessel Name: Willy
Vessel Model: Willard Nomad 30'
Join Date: Oct 2007
Posts: 13,707
OD yes.
There seems to be more different kinds of SS than steel.

Are bronze machine screws readily availible. Wood screws a-plenty but machine screws?
__________________
Eric

North Western Washington State USA
Nomad Willy is offline   Reply With Quote
Old 04-02-2015, 11:52 PM   #18
Guru
 
Xsbank's Avatar
 
City: Pender Harbour, BC
Country: Canada
Vessel Name: Gwaii Haanas
Vessel Model: Vancouver Shipyards Custom Aluminum 52
Join Date: Sep 2013
Posts: 2,443
Stainless screws in aluminum will corrode the aluminum and frequently the threads will gall, causing the fastener to fail when you try and undo it. I have some 316 stainless hardware, which is very good but hard to find and expensive. I have some on the boat as the previous owner worked at a pulp mill and I think some of them followed him home. Lucky for me, the mill has closed!

Brass is the wrong alloy for boats, bronze is much better.

The radio tower mentioned is likely not bathed in salt water.
__________________
Don't believe everything that you think.
Xsbank is offline   Reply With Quote
Old 04-03-2015, 07:32 AM   #19
Guru
 
caltexflanc's Avatar
 
City: North Carolina for now
Country: USA
Vessel Name: Small Incentive
Vessel Model: Boston Whaler 130 Sport
Join Date: Aug 2011
Posts: 3,785
Quote:
Originally Posted by manyboats View Post
OD yes.
There seems to be more different kinds of SS than steel.

Are bronze machine screws readily availible. Wood screws a-plenty but machine screws?
Jamestown has them: Fastener Type: Machine Screws

The only thing I use them for is for fastening bronze fixtures together like through hulls, strainers etc.
__________________
George

"There's the Right Way, the Wrong Way, and what some guy says he's gotten away with"
caltexflanc is online now   Reply With Quote
Old 04-03-2015, 08:59 AM   #20
TF Site Team
 
Larry M's Avatar
 
City: JAX, FL
Country: USA
Vessel Name: Hobo
Vessel Model: Krogen 42-120
Join Date: Nov 2008
Posts: 5,725
In our sail boat days and when we re-rigged the mast on Hobo, in addition to using Duralac, we secured some of the hardware with either ss or monel pop rivets. If remove is (was) required later, all you have to do is drill out the rivet. No worries about the rivet galling like you potentially have with screws.
__________________

Larry M is online now   Reply With Quote
Reply

Thread Tools
Display Modes

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 -5. The time now is 11:15 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012