81 GCAT 5.0 Rebuild :: Catamaran Sailboats at TheBeachcats.com

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81 GCAT 5.0 Rebuild

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rockypointbob

Rank: Lubber

Registered: Jul 13, 2017

Last visit: Sep 28, 2020

Posts: 30
Posted: Sep 14, 2017 - 11:33 PM

jsb4g
rockypointbobWhen I had the hulls refinished, I had the body guy build up the transoms so they should be pretty sturdy now. Looking at the pic (which I got from Hans FB site) I posted of the correct mounting of the gudgeons, it appears they also used SS sheet metal screws for the brackets.

I have inspection ports on both hulls but they are too far forward to reach the transom. I've had the boat out with the rudders mounted incorrectly (I had no idea at the time) and it worked great, but what do I know, it was my first time solo on a boat! So I guess the answer is to have two more ports installed such that we can do backing plates. Bummer.

What about the Dotan kick-up rudder system? Guess I would have the same issue with mounting?

I don't know anything about the Dotan system. I defer to MN3 re sheet metal screws vs bolts. It makes sense that bolts would be better. As for leaving as is, since repairing it correctly is a major undertaking, you could just leave it as is, but remember this thread if you encounter issues later. Lastly, I will be going sailing this weekend, so I will be able to measure any parts you want measured. I remember you wanted the rudder pin length and diameter measured. I am using clevis pins right now, but I have the original long rudder pins too. Was there anything else?

I'm actually headed down to Mexico this weekend so I'll be able to finally see all the parts, take measurements, etc. But thanks much for the info on the traveler car; got it in today. I guess I will leave the rudders as is for now and until I actually get to the point of flying a hull, which will probably not be anytime soon. Actually, there is one thing that would be most helpful...some good pics of your jib rigging. I feel pretty confident with rebuilding the mainsheet rigging but not so much with the jib. I've seen some pic of a Gcat 5.0 barber-haul set up but they weren't very clear. Thank You!
rockypointbob

Rank: Lubber

Registered: Jul 13, 2017

Last visit: Sep 28, 2020

Posts: 30
Posted: Sep 14, 2017 - 11:35 PM

MN3the more i think of this, the more i think it is ok how it is
i am no engineer but i think the sheer forces would not be changed by this set up, or if they are changed it isn't by much

i am certain self tapping is not the correct solution
adding ports is not optimal nor fun work

i think i would leave it as is

hopefully one of our engineers on here will comment too

I think I'm going to go with it as it is since I've sailed it twice and seemed to be ok...at least for now.
MN3

Rank: Master Chief

Registered: Jun 20, 2006

Last visit: Dec 04, 2024

Posts: 7090
Posted: Sep 14, 2017 - 11:46 PM

QuoteI think I'm going to go with it as it is since I've sailed it twice and seemed to be ok...at least for now.

just cause it didn't explode the last 2 times doesn't mean it won't
you should really deeply inspect and test it, wiggle it (just a little bit) - jk - wiggle it a decent amount
and keep an eye on it (inspect it a few times) under sail

the forces get much bigger with speed - i think i read the tension of the rigging doubles every 7 knots (or something like that)

I'm not 100% sure that the casting resting on the gudgeon doesn't increase shear ... so please look a little deeper than my advice alone - i would feel bad if you rip your transom off hitting ground or surf (and it was due to my best guess)
rockypointbob

Rank: Lubber

Registered: Jul 13, 2017

Last visit: Sep 28, 2020

Posts: 30
Posted: Sep 14, 2017 - 11:55 PM

dmgbear55I had good success using the Awlgrip system on all of my aluminum on This End Up. Steps were to sand the anodizing, use their wash coat, next up was the 545 epoxy primer, then used the Awlgrip 2000. Paint is never going to be as durable as anodizing, but there are very few places to get a mast anodized.

I am very satisfied with the appearance and the durability of this finish system. It was a lot of work though for a DIY project. If you are using professionals they likely could work through this pretty quickly. Me not so much.

Here is the album on the aluminum work on my project:

https://www.thebeachcats.…ictures?g2_itemId=123176

Wow. That does look like a major project! But the end result is great. I think I will get everything else squared away then leave that for last....or buy a new boat!
rockypointbob

Rank: Lubber

Registered: Jul 13, 2017

Last visit: Sep 28, 2020

Posts: 30
Posted: Sep 15, 2017 - 12:11 AM

MN3
QuoteI think I'm going to go with it as it is since I've sailed it twice and seemed to be ok...at least for now.

just cause it didn't explode the last 2 times doesn't mean it won't
you should really deeply inspect and test it, wiggle it (just a little bit) - jk - wiggle it a decent amount
and keep an eye on it (inspect it a few times) under sail

the forces get much bigger with speed - i think i read the tension of the rigging doubles every 7 knots (or something like that)

I'm not 100% sure that the casting resting on the gudgeon doesn't increase shear ... so please look a little deeper than my advice alone - i would feel bad if you rip your transom off hitting ground or surf (and it was due to my best guess)

Will do. Once I get her back together, I'll wiggle it around then take her for a slow spin and watch if it flexes. etc. So there should already be a SS backing plate installed when the hull was put together? I wonder how others have repaired problems with the mounts without an inspection port.
dmgbear55

Rank: Mate

Registered: Jun 22, 2015

Last visit: Jul 06, 2018

Posts: 258
Posted: Sep 15, 2017 - 12:21 AM

Or buy another old boat. I am now a year into a J30 monohull. Things I learned on the 5.2 apply to this new project too. None of this stuff is simple or easy. I like researching techniques and other people's experiences and then figuring out what I want to do. Resources like beachcats.com are invaluable to those of us taking a little different course.

I wish I could say that recycling an old boat like This End Up is the green thing to do, but all the overspray in my shop says otherwise. But my Nacra 5.2 looks almost as good as any boat fresh off the showroom floor, maybe better with those killer tangerine sails and dark blue hulls. The experience from all these guys watching this site is key to getting to a great final result.

One of these days soon my woodshop will be back to being a woodshop rather than a boat shop, but that will happen when it happens. Fooling around with boats is keeping my back in pain, my arms in pain, my wallet in pain, god I love this stuff.

--
dg
NACRA 5.2 #400
This End Up
Original owner since 1975
--
jsb4g

Rank: Lubber

Registered: Oct 11, 2016

Last visit: Jun 19, 2018

Posts: 42
Posted: Sep 15, 2017 - 08:01 AM

rockypointbob

Will do. Once I get her back together, I'll wiggle it around then take her for a slow spin and watch if it flexes. etc. So there should already be a SS backing plate installed when the hull was put together? I wonder how others have repaired problems with the mounts without an inspection port.

I don't think the boat was built with a backing plate. If there had been one, this would not be such a common problem. My biggest concern would be your screws coming loose over time and you not noticing
MN3

Rank: Master Chief

Registered: Jun 20, 2006

Last visit: Dec 04, 2024

Posts: 7090
Posted: Sep 15, 2017 - 09:58 AM

QuoteSo there should already be a SS backing plate installed when the hull was put together?

Unknown -
i looked at hanz's current 5.0 and it has no real access via his 4" access ports - who knows

QuoteI wonder how others have repaired problems with the mounts without an inspection port.

a. the accepted their fate and added a port (it's not THAT hard - but like everything, there is skill involved so it's easy to have issues if you never have done it before)

b. did invasive surgery (i.e. remove a section of the transom to add the plate and then reattached it)
anything can be "repaired" - just a question of funds, time and desire

c. smathered 5200 (or epoxy, or something) everywhere in an attempt to secure the gudgeon on the external section - which may or maynot last depending how strong it is and what forces it meets
klozhald

Rank: Chief

Registered: Apr 19, 2011

Last visit: Feb 19, 2025

Posts: 1462
Posted: Sep 15, 2017 - 01:15 PM

dmgbear55I wish I could say that recycling an old boat like This End Up is the green thing to do, but all the overspray in my shop says otherwise.

It is green because you can repair it to usability, and doing so consumes less material than you would if you scrapped it and bought another, A huge part of sustainability is getting away from disposable attitudes in all things.

Dmgbear you are more sustainable than you give yourself credit for.

--
Sheet In!
Bob
_/)_____/)_/)____/)____/)_____/)/)__________/)__
Prindle 18-2 #244 "Wakizashi"
Prindle 16 #3690 "Pegasus" Sold (sigh)
AZ Multihull Fleet 42 member
(Way) Past Commodore of Prindle Fleet 14
Arizona, USA
--
MN3

Rank: Master Chief

Registered: Jun 20, 2006

Last visit: Dec 04, 2024

Posts: 7090
Posted: Sep 15, 2017 - 03:49 PM

QuoteDmgbear you are more sustainable than you give yourself credit for.

+1

and most of that overspray will live in your shop (walls and ceilings, and more) forever! never seeing a dump - well played sir!
jsb4g

Rank: Lubber

Registered: Oct 11, 2016

Last visit: Jun 19, 2018

Posts: 42
Posted: Sep 20, 2017 - 08:04 PM

MN3
QuoteSo there should already be a SS backing plate installed when the hull was put together?

Unknown -
i looked at hanz's current 5.0 and it has no real access via his 4" access ports - who knows

I actually know, but maybe not. Afterall, I just own the boat and have seen what an original one looked like when the transom ripped off in surf. Inspecting Hans' port holes seems a little invasive...maybe just ask him????

Edited by jsb4g on Sep 20, 2017 - 08:11 PM.
rockypointbob

Rank: Lubber

Registered: Jul 13, 2017

Last visit: Sep 28, 2020

Posts: 30
Posted: Sep 21, 2017 - 12:01 AM

Well, after my trip to Mexico this past weekend, I feel much better about the condition of the boat. At least while it is on shore! We removed each cross beam and replaced all the hardware with spec components. Replaced all the standing rigging to include the shroud line anchor pins. And we inspected and checked the mounts for the rudders. So far, everything seems pretty solid. While inspecting the rudder (gudgeons?), I did attempt to see if the flanges fit inside the mounts..and in fact they do...like a glove. So no doubt they are currently incorrectly mounted...but seem to work. So at some point in time I will feel the need to do it right and maybe have to install an inspection port at each end of the hull to install some sort of backing plate(s).

But next step is coming up, which will be replacing all the running rigging...and then getting her back in the Sea of Cortez.

JSB4G, did you have a chance to take some pics of your barber haul this past weekend? This would be most helpful.

Heading to San Diego this weekend to take some classes....maybe fly a hull for the first time
rockypointbob

Rank: Lubber

Registered: Jul 13, 2017

Last visit: Sep 28, 2020

Posts: 30
Posted: Sep 21, 2017 - 12:05 AM

Anyone know any good shops in San Diego to buy sail boat parts? I want to get a few things while I'm there....thanks
MN3

Rank: Master Chief

Registered: Jun 20, 2006

Last visit: Dec 04, 2024

Posts: 7090
Posted: Sep 21, 2017 - 09:53 AM

Quote did attempt to see if the flanges fit inside the mounts..and in fact they do...like a glove. So no doubt they are currently incorrectly mounted...but seem to work

looking at the pic again, it may be as simple as the bottom gudgeons is mounted upside down -

QuoteHeading to San Diego this weekend to take some classes....maybe fly a hull for the first time icon_biggrin

awesome! great idea
MN3

Rank: Master Chief

Registered: Jun 20, 2006

Last visit: Dec 04, 2024

Posts: 7090
Posted: Sep 25, 2017 - 11:16 AM

I crewed with Hans yesterday
there is an alum plate glassed in the transom (as does my cat)
you should be able to tap threads into it -
i still would simply try turning the gudgeon 180*

Edited by MN3 on Sep 25, 2017 - 11:52 AM.
jsb4g

Rank: Lubber

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Posts: 42
Posted: Sep 25, 2017 - 08:23 PM

MN3I crewed with Hans yesterday
there is an alum plate glassed in the transom (as does my cat)
you should be able to tap threads into it -
i still would simply try turning the gudgeon 180*Edited by MN3 on Sep 25, 2017 - 11:52 AM.

I applaud you for asking for advice and then passing it on instead of speculating. Did Hans put the metal plate there as a repair/upgrade? I know his rudder system is not original. Also, I have seen multiple G-Cats with the rear transom ripped off and they had to be rebuilt. I have never seen a metal plate on an original, unrebuilt Gcat. I can send you a pick of a damaged original if you'd like. what do you mean by turning the gudgeon 180 degrees?

Edited by jsb4g on Sep 25, 2017 - 08:25 PM.
kitesurfer2

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Registered: Oct 27, 2017

Last visit: Nov 01, 2017

Posts: 6
Posted: Oct 27, 2017 - 07:18 AM

good thread! I just bought a g cat in 'good' condition a couple weeks ago. I have not sailed it yet as too many things need to be fixed or replaced. My rudders are attached the exact same way as yours.