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Old 07-06-2016, 09:19   #1
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How to mount genoa t-track on gunwale

I'm completing refit of Winward Marine Searaker 50. The boat is supposed to have a 24' 1 1/2" genoa t-track on both side decks. I'd really like to mount the t-track to the side of the gunwale so I don't have so many holes through the deck. The gunwale rises off the deck about 2" and tapers from a 2" base to 1.5" wide at the top. The gunwale is integral to the hull and deck and also contains the hull to deck joint.

I'm considering using 6061-T6 2" x 2" x 3/8" anodized aluminum angle and mount that to the inside of the gunwale using 1/2" SS through bolts every 6".

The Schaefer cars that I've purchased for the t-track are rated for 5000lb load, so based on the calculations I've made, this 2" aluminum angle through bolted every 6" with 1/2 SS bolts and the 1 1/2" stainless t-track through bolted to the angle every 4" with 3/8" SS bolts should handle at least 10,000lb.

What am I missing here?

Thanks

Chris
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Old 07-06-2016, 09:40   #2
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Re: How to mount genoa t-track on gunwale

Don't use aluminum angle and SS bolts, you'll be amazed at how quickly it corrodes and turns into a bunch of white powder.... especially in that location. Not sure of the answer, but maybe SS Angle. SS T track used to be available also... You are mounting the track on the angle to make the track orientation like it would be sitting on deck right? Good thought, Not sure if there are any blocks that would be ok to avoid the angle use or not.
Also, keep in mind that that bulwark may be hollow.


Another question to ask yourself is, what sails are you going to use and do you really need 24 ft of track? You may only need half that, and thru bolting the deck may be a lot less complicated and problematic.
Just my thoughts.
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Old 07-06-2016, 10:08   #3
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Re: How to mount genoa t-track on gunwale

Make sure it's not just the hardware store kind of anodizing on the angle. It needs to be the good hard stuff which would hold up to ss bolts and just about anything else. Where can you get that?
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Old 07-06-2016, 14:03   #4
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Re: How to mount genoa t-track on gunwale

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Make sure it's not just the hardware store kind of anodizing on the angle. It needs to be the good hard stuff which would hold up to ss bolts and just about anything else. Where can you get that?
I purchased the aluminum angle from onlinemetals.com. Its 6061-T6 structural aluminum angle, very strong. I use a 12 ton pipe bender to put a slight curve in it to fit the curve of the gunwale and it takes quite a bit of force to bend. Then I send it out to a local shop and get it anodized. I always isolate stainless from aluminum using nylon or G10 washers/bushings and a healthy application of TefGel for good measure.

For clarification, the gunwale is solid. The hull to deck joint was glassed over from the inside and the gap in the gunwale was completely filled with resin mixed with micro balloons and then the cap on the gunwale glassed over with 6 layers of fiberglass cloth. Its about as sturdy as you can make it.
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Old 08-06-2016, 08:52   #5
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Re: How to mount genoa t-track on gunwale

I dont know the design. But, it may change your sheeting angles substantially. I would really consider speaking with a local sailmaker (and paying him) about how the sheeting angles will affect the pointing ability of the boat. All I can envisage is either a sheet that is too far out to point properly or one that needs to be sheeted so far aft that the leech opens too far and loses power.

Re -using stainless fasteners with alloy track, there use to be nylon/plastic bushes/sleeves that are counter sunk that can go into the track to prevent galvanic issues. I assume they still exist. The name escapes me. If I think of it, I will post it.
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Old 08-06-2016, 09:09   #6
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Re: How to mount genoa t-track on gunwale

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I purchased the aluminum angle from onlinemetals.com. Its 6061-T6 structural aluminum angle, very strong. I use a 12 ton pipe bender to put a slight curve in it to fit the curve of the gunwale and it takes quite a bit of force to bend. Then I send it out to a local shop and get it anodized. I always isolate stainless from aluminum using nylon or G10 washers/bushings and a healthy application of TefGel for good measure.

For clarification, the gunwale is solid. The hull to deck joint was glassed over from the inside and the gap in the gunwale was completely filled with resin mixed with micro balloons and then the cap on the gunwale glassed over with 6 layers of fiberglass cloth. Its about as sturdy as you can make it.
A good heavy hard coat anodize should be fine. I thought you were using regular old aluminum angle. Be sure to drill your holes prior to anodizing!
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Old 08-06-2016, 09:42   #7
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Re: How to mount genoa t-track on gunwale

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I dont know the design. But, it may change your sheeting angles substantially. I would really consider speaking with a local sailmaker (and paying him) about how the sheeting angles will affect the pointing ability of the boat. All I can envisage is either a sheet that is too far out to point properly or one that needs to be sheeted so far aft that the leech opens too far and loses power.

Re -using stainless fasteners with alloy track, there use to be nylon/plastic bushes/sleeves that are counter sunk that can go into the track to prevent galvanic issues. I assume they still exist. The name escapes me. If I think of it, I will post it.
You make a really good point about the sheeting angle and I have considered that. The reality is that the track is only moving about 4" outboard of where it would have been located on the deck. I'm also planning on moving the lifeline stanchions to the gunwale cap using G10 rods glassed into the hull so that the sheets remain inboard of the lifelines, as they would have normally been. This also saves me another 24 holes in the deck from the stanchions. Otherwise, I would have had over 100 holes through the deck on each side. Yikes!
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Old 08-06-2016, 09:59   #8
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Re: How to mount genoa t-track on gunwale

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Originally Posted by wgoodbye View Post
...I'm also planning on moving the lifeline stanchions to the gunwale cap using G10 rods glassed into the hull...
Sounds very weak.

Quote:
Originally Posted by wgoodbye View Post
...the gunwale was completely filled with resin mixed with micro balloons...
Microballoons are for fairing and have very little strength. You should have used a high density filler, instead.
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Old 08-06-2016, 10:09   #9
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Re: How to mount genoa t-track on gunwale

i had the same issue a few years back.
my bulwark was wide enough that I drilled over size holes in the teak toe rail then a bit smaller holes deep into the hull to deck fiberglass then filled them with atrong mixe of epox and high density filler after that hardened i drilled and tapped for every bolt for the track.. I have had no issues with this installation
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Old 08-06-2016, 10:21   #10
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Re: How to mount genoa t-track on gunwale

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Originally Posted by Terra Nova View Post
Sounds very weak.
Microballoons are for fairing and have very little strength. You should have used a high density filler, instead.
Using 1"G-10 rod material for a lifeline stanchion is way stronger than a bolted down steel tube.
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Old 08-06-2016, 10:26   #11
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Re: How to mount genoa t-track on gunwale

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Using 1"G-10 rod material for a lifeline stanchion is way stronger than a bolted down steel tube.
The crosswise tensile strength of G10 rod is 35,000 PSI. I'm using 3/4" rod, which makes it several times stronger than the .065 wall 1" SS stanchion tubes. The stanchions will bend or break before the rod does.
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Old 08-06-2016, 11:10   #12
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Re: How to mount genoa t-track on gunwale

Hi Chris

6061-T6 2" x 2" x 3/8 is tough it should be easily strong enough for your application (note: I have not done any formal calculations just using the principal if it looks right it should be OK). Your goal of minimising the deck penetrations is a sensible aim. With offshore sailing the flexing of the fibreglass deck does have a risk of leaks. With the multitude of deck penetrations in a typical genoa track the risk of a leak from at least one of the holes is significant. I think you are wise to try and elimate this possibility. Salt water dripping on the cushions/bedding is the pits. If it wetting the deck core material the long term consequences are even more serious.

An aluminium track with stainless steel bolts and stainless car is commonly used, but with the high mass of stainless steel in relation to the amount of aluminium dissimilar metal corrosion is inevitable. Most genoa tracks and even aluminium toe rails have a similar construction and while in many ways it is a very poor use of aluminium in practice the aluminium has a reasonable service life. Ideally, especially for the toe rail and the critical hull to deck joint there are perhaps better solutions. At least isolate the aluminium from the SS as much as possible given there is only a small mass of aluminium.

A couple of suggestions:

6082 aluminium is stronger and more corrosion resistant than 6061. It anodises just as well and would be a slightly better choice if it available locally.

Have you considered low friction rings instead of a track? These can be barber hauled, which would eliminate the problem of the larger sheeting angle. It reduces the amount of SS, reducing the potential for corrosion. It's cheaper and more reliable.

Let us know how well it works in practice no matter what you decide.
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Old 08-06-2016, 11:45   #13
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Re: How to mount genoa t-track on gunwale

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Hi Chris

6061-T6 2" x 2" x 3/8 is tough it should be easily strong enough for your application (note: I have not done any formal calculations just using the principal if it looks right it should be OK). Your goal of minimising the deck penetrations is a sensible aim. With offshore sailing the flexing of the fibreglass deck does have a risk of leaks. With the multitude of deck penetrations in a typical genoa track the risk of a leak from at least one of the holes is significant. Salt water dripping on the cushions/bedding is the pits.

An aluminium track with stainless steel bolts and stainless car is commonly used, but with the high mass of stainless steel in relation to the amount of aluminium dissimilar metal corrosion is inevitable. Most genoa tracks and even aluminium toe rails have a similar construction and while in many ways it is a very poor use of aluminium in practice the aluminium has a reasonable service life, although, ideally, especially for the toe rail and the critical hull to deck joint there are perhaps better solutions.

A couple of suggestions:

6082 aluminium is stronger and more corrosion resistant than 6061. It anodises just as well and would be a slightly better choice if it available locally.

Have you considered low friction rings instead of a track? These can be barber hauled, which would eliminate the problem of the larger sheeting angle. It reduces the amount of SS, reducing the potential for corrosion. It's cheaper and more reliable.

Let us know how well it works in practice no matter what you decide.
Thank you very much for your comments. As a point of clarity, the actual t-track itself is SS (came with the boat, never installed). I will isolate the SS from the angle aluminum with some 1/4" G10. I would have used SS angle also but its about 8X the cost of the aluminum.
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Old 08-06-2016, 12:22   #14
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Re: How to mount genoa t-track on gunwale

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I will isolate the SS from the angle aluminum with some 1/4" G10. I would have used SS angle also but its about 8X the cost of the aluminum.
I did not realise you were mounting a SS track on the aluminium section.

It is tough to isolate the SS from the aluminium in this sort of application. The G10 will isolate the base, but even with Duralac/Tuffgel/plastic inserts there will be some electrical connection between the aluminium and SS via the attachment bolts.

A multimeter will provide a final check, but even with the best practice you're likely to get a low ohm reading between the SS and aluminium.

This dissimilar metal interaction is not a concern with a high mass of aluminium (say an aluminium hull) and a small amount of SS.

In your application you have a much smaller mass of aluminium with a high mass of SS track and bolts. I think you are likely to get some significant corrosion, at least in the long term. Schaefer products are well constructed but in this application mounting a SS track on top of aluminium section is not ideal. Most genoa tracks from alternative manufacturers are aluminium. These would be a better choice for mounting on top of aluminium section. Alternatively if using a SS track I would use a SS section.
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