BarraMan's Mangusta 21 barraboat in Townsville, AUS

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OlivierP
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Re: BarraMan's Mangusta 21 barraboat in Townsville, AUS

Post by OlivierP »

Interesting, I've never glued cloth upside down (nor down under...) so interested to see how it goes.

Did you consider a keel guard or keel shield type protection ?
Built C17 (app.php/gallery/album/262), GF14, Devlin Bella 16. Sails a 30ft Biloup 89 sailboat.

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BarraMan
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Re: BarraMan's Mangusta 21 barraboat in Townsville, AUS

Post by BarraMan »

OlivierP wrote: Thu Aug 17, 2023 5:19 pm Interesting, I've never glued cloth upside down (nor down under...) so interested to see how it goes.
Did you consider a keel guard or keel shield type protection ?
Its awkward, but doable! I used an engine crane to lift the front of the boat so that I could get to the affected area.

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Now I am on to graphite, high-build priming, and painting!

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I had a Keel Guard on the boat when first built. At that time the boat was on a bunk trailer so the keel was not resting on anything. Unfortunately, one fishing trip to the remote north of Australia destroyed the torsion bar suspension on that trailer, so I had a new custom built trailer made with roller-rocker spring suspension. The builder convinced me to go with roller support for the boat. As that meant to Keel Guard would be sitting on a roller ladder, I removed it as they say not to use Keel Guard with rollers.

I now intend to fit Keel Guard to the boat again, but only run it to just before the keel touches to first roller - which should protect the vulnerable area. Where we fish mostly has a sand or mud bottom, so I think the damage occurred at the dam where we ski at Xmas time, which has a stony bottom. I will be more conscious of that in future. We'll see how it goes, in the meantime I am happy to have an additional 6x layers of glass between the external hull and the wood core. :D

3x coats of graphite/epoxy 1/3:2/3 by volume!

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Re: BarraMan's Mangusta 21 barraboat in Townsville, AUS

Post by Fuzz »

Lee how many layers of glass did the hull have where it was worn through?

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Re: BarraMan's Mangusta 21 barraboat in Townsville, AUS

Post by OneWayTraffic »

I'd rethink that keel guard idea. The FAQ for Keelshield says that if there's weight bearing rollers, even if just when loading or unloading that it can become an issue.

I glued an aluminium strip to mine. Just a bunnings 2mm by 30mm profile. Glued with gflex. On the sides I have UHMWPE flame treated then also glued with gflex. Both of which should be a lot more resistant to rollers than a Keelshield, at a fraction of the cost.

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BarraMan
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Re: BarraMan's Mangusta 21 barraboat in Townsville, AUS

Post by BarraMan »

Fuzz wrote: Sat Aug 19, 2023 12:53 am Lee how many layers of glass did the hull have where it was worn through?
9 x layers of 12oz biax
4 x coats of graphite/epoxy
4 x coats of epoxy primer (sanded back somewhat)
2 x coats of 2 pack polyurethane under coat
2 x coats of 2 pack polyurethane top coat
:D

The rubs are only 2 areas each about 2” long - so my repairs are probably overkill!

95% of the ‘at risk’ area now has 15 x layers of 12oz biax to get thru before the wood core is exposed! :D
Last edited by BarraMan on Sat Aug 19, 2023 8:56 am, edited 2 times in total.

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BarraMan
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Re: BarraMan's Mangusta 21 barraboat in Townsville, AUS

Post by BarraMan »

OneWayTraffic wrote: Sat Aug 19, 2023 6:53 am I'd rethink that keel guard idea. The FAQ for Keelshield says that if there's weight bearing rollers, even if just when loading or unloading that it can become an issue.
I glued an aluminium strip to mine. Just a bunnings 2mm by 30mm profile. Glued with gflex. On the sides I have UHMWPE flame treated then also glued with gflex. Both of which should be a lot more resistant to rollers than a Keelshield, at a fraction of the cost.
I already have the Keel Guard so I’ll give it a go. If it doesn’t work out I’ll run an aluminium strip when I have the boat out on hard stand! :D

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Re: BarraMan's Mangusta 21 barraboat in Townsville, AUS

Post by fallguy1000 »

BarraMan wrote: Sat Aug 19, 2023 8:49 am
OneWayTraffic wrote: Sat Aug 19, 2023 6:53 am I'd rethink that keel guard idea. The FAQ for Keelshield says that if there's weight bearing rollers, even if just when loading or unloading that it can become an issue.
I glued an aluminium strip to mine. Just a bunnings 2mm by 30mm profile. Glued with gflex. On the sides I have UHMWPE flame treated then also glued with gflex. Both of which should be a lot more resistant to rollers than a Keelshield, at a fraction of the cost.
I already have the Keel Guard so I’ll give it a go. If it doesn’t work out I’ll run an aluminium strip when I have the boat out on hard stand! :D
What about getting rid of the front rollers and making some glide bunks..you know where to put them!
My boat build is here -------->

viewtopic.php?f=12&t=62495

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Re: BarraMan's Mangusta 21 barraboat in Townsville, AUS

Post by Fuzz »

Seems like a lot of glass to rub through. Are you sure you have not been "rubbing" on some rocks at 30 knots or so :doh:

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BarraMan
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Re: BarraMan's Mangusta 21 barraboat in Townsville, AUS

Post by BarraMan »

Fuzz wrote: Sun Aug 20, 2023 12:10 am Seems like a lot of glass to rub through. Are you sure you have not been "rubbing" on some rocks at 30 knots or so :doh:
Well, I have had two big “hits” with the boat on unknown rocks/pinnacles in the middle of nowhere, but they were taken by the skeg not the hull! :doh:

I guess I should have taken pics of the rubs, but they were only 2x spots about 2” long each, separated by 1x foot or so.

I have run aground unexpectedly many times but only on sand or mud!

My only explanation for the rubs is that they have happened over a number of years during our annual Xmas holidays when we spend a week or so waterskiing at a dam where the shoreline is stoney where I park the boat when launching and retrieving - no pontoon!

Some other rub areas down to the graphite only, but like you, I am surprised at the rubs through 9 layers of glass! 8O

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Re: BarraMan's Mangusta 21 barraboat in Townsville, AUS

Post by OlivierP »

My experience too, glass is not so resistant to rubbing. Waves impact, torsional forces yes, but for rubbing kevlar cloth will likely be more efficient.
Built C17 (app.php/gallery/album/262), GF14, Devlin Bella 16. Sails a 30ft Biloup 89 sailboat.

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