Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 18-12-2011, 14:14   #1
Registered User

Join Date: Sep 2005
Boat: Nordhavn 50
Posts: 85
Question rudder repair: kevlar??

Hi all

I'm in the process of tackling a winter project which is to repair my rudder. I have watched over the last five years or so, the apearance of hairline cracks at first on the bottom third, across and both sides. Pretty much at the level where the rudder stock (fiberglass) ends inside. Year after year new cracks appeared in no particular patterns, and more and more toward the top. Every spring I seamed to notice new ones eventough from the time it started, I started drilling weep holes at the bottom every fall. Never seen any drainage from hole, but one or two spots along crack would weep.

So this year having brought my boat home, I decided to do something about it. Took the rudder off the boat. Brought it home. Sanded the gelcoat off it. Now seeing the full extent of damage. I Vee grinded all the crack, drilled some holes. No drainage per se, but 3 or 4 humid circles around a few holes.

Rudder is foam cored and laminate seems to be only chopped mat (or gun!??). As I said fiberglass stock, tabing ??metal?? inside.

My plan is to let it dry more, not necessarily open it more. Then was thinking of laminating two layer of kevlar 5 oz with West System Epoxy.

Initialy I was convinced it was water inside and freeze thaw cycle responsible. Now wandering if it wasn't more stress?? I'm not an expert..
Does this plan sound good.? Should I stick to fiberglass (fabric vs stich-mat vs ?) or kevlar or hybrid? Epoxy or vinylester resin?

Any advices?

Thanks in advance

Michel
__________________

__________________
siroismi is offline   Reply With Quote
Old 18-12-2011, 14:21   #2
Moderator
 
Pete7's Avatar

Cruisers Forum Supporter

Join Date: Aug 2009
Location: Solent, England
Boat: Moody 31
Posts: 8,578
Images: 14
Re: rudder repair: kevlar??

Michel,

I would stick with epoxy and cloth because it's a known material. Kevlar is expensive and needs special scissors to cut it for a start. You might also find the strength is directional, whilst you will want uni-directional.

Keep it simple (kiss) approach for me.

Pete
__________________

__________________
Moody 31 - April Lass
Pete7 is offline   Reply With Quote
Old 18-12-2011, 14:32   #3
CF Adviser
 
Bash's Avatar

Cruisers Forum Supporter

Join Date: Dec 2008
Location: sausalito
Boat: 14 meter sloop
Posts: 7,260
Re: rudder repair: kevlar??

check out this blog Fiberglass Materials: Exotics
__________________
cruising is entirely about showing up--in boat shoes.
Bash is offline   Reply With Quote
Old 18-12-2011, 14:44   #4
Senior Cruiser
 
atoll's Avatar

Cruisers Forum Supporter

Join Date: Mar 2010
Location: gettin naughty on the beach in cornwall
Boat: 63 custom alloy sloop,macwester26,prout snowgoose 37 elite catamaran!
Posts: 9,312
Images: 75
Re: rudder repair: kevlar??

i wouldnt bother with kevlar,but would reccomend doing a full rebuild on the rudder ie split the two halves,take out the soggy foam,inspect the stainless shaft and stiffners,then reassemble using pu foam and reglassing the two halves,only this way will you be sure of a proper repair,glassing the outside ,if the inside has deteriated is not going to fix the problem
__________________
my catamaran building project updates http://www.cruisersforum.com/forums/...36#post2502136
atoll is offline   Reply With Quote
Old 18-12-2011, 14:53   #5
Registered User

Join Date: Mar 2009
Location: Sydney
Boat: Lexcen 40 - Leverage
Posts: 383
Re: rudder repair: kevlar??

Quote:
Originally Posted by siroismi View Post
Hi all

I'm in the process of tackling a winter project which is to repair my rudder. I have watched over the last five years or so, the apearance of hairline cracks at first on the bottom third, across and both sides. Pretty much at the level where the rudder stock (fiberglass) ends inside. Year after year new cracks appeared in no particular patterns, and more and more toward the top. Every spring I seamed to notice new ones eventough from the time it started, I started drilling weep holes at the bottom every fall. Never seen any drainage from hole, but one or two spots along crack would weep.

So this year having brought my boat home, I decided to do something about it. Took the rudder off the boat. Brought it home. Sanded the gelcoat off it. Now seeing the full extent of damage. I Vee grinded all the crack, drilled some holes. No drainage per se, but 3 or 4 humid circles around a few holes.

Rudder is foam cored and laminate seems to be only chopped mat (or gun!??). As I said fiberglass stock, tabing ??metal?? inside.

My plan is to let it dry more, not necessarily open it more. Then was thinking of laminating two layer of kevlar 5 oz with West System Epoxy.

Initialy I was convinced it was water inside and freeze thaw cycle responsible. Now wandering if it wasn't more stress?? I'm not an expert..
Does this plan sound good.? Should I stick to fiberglass (fabric vs stich-mat vs ?) or kevlar or hybrid? Epoxy or vinylester resin?

Any advices?

Thanks in advance

Michel
I had a similar problem earlier this year during my haulout - but probably of a more impressive nature.

The entire rudder's foam core was soaked.

So I cut the skins off both sides, leaving the trailing and leading edges intact,dried with a hot air gun (paying $200/day for hardstand means I can't wait 2-3 months to let dry properly. :\

Ground all bonding edges back with a taper.

Place rudder on side, pour in two part foam bit by bit and fill every nook and cranny.

Rasp/sand/grind foam back to shape.

Mix up microballoons/West 411 in a thinnish mix and trowel all over the foam to get a smooth, non-porous surface.

Grind/sand back to shape.

Another mix of thin 411, trowelled on and packing the remaining porosity etc...

Grind/sand/fondle to shape.

Then layup glass, overlapping on leading/trailing edges: 1 (or two? can't remember) layer of 750gsm triaxial, then 2 layers of 450 gsm biaxial.

Grind/sand back to shape.

Fairing compound.

Grind/sand/fondle...

4 coats of Barrier coat.

2 coats of antifoul.

voila...

(don't use anything but epoxy btw, these are all secondary bonds)
__________________
akio.kanemoto is offline   Reply With Quote
Old 18-12-2011, 15:01   #6
Senior Cruiser
 
atoll's Avatar

Cruisers Forum Supporter

Join Date: Mar 2010
Location: gettin naughty on the beach in cornwall
Boat: 63 custom alloy sloop,macwester26,prout snowgoose 37 elite catamaran!
Posts: 9,312
Images: 75
Re: rudder repair: kevlar??

Quote:
Originally Posted by akio.kanemoto View Post
I had a similar problem earlier this year during my haulout - but probably of a more impressive nature.

The entire rudder's foam core was soaked.

So I cut the skins off both sides, leaving the trailing and leading edges intact,dried with a hot air gun (paying $200/day for hardstand means I can't wait 2-3 months to let dry properly. :\

Ground all bonding edges back with a taper.

Place rudder on side, pour in two part foam bit by bit and fill every nook and cranny.

Rasp/sand/grind foam back to shape.

Mix up microballoons/West 411 in a thinnish mix and trowel all over the foam to get a smooth, non-porous surface.

Grind/sand back to shape.

Another mix of thin 411, trowelled on and packing the remaining porosity etc...

Grind/sand/fondle to shape.

Then layup glass, overlapping on leading/trailing edges: 1 (or two? can't remember) layer of 750gsm triaxial, then 2 layers of 450 gsm biaxial.

Grind/sand back to shape.

Fairing compound.

Grind/sand/fondle...

4 coats of Barrier coat.

2 coats of antifoul.

voila...

(don't use anything but epoxy btw, these are all secondary bonds)
ditto that,if you have somewhere nice to work it is not that much of a complex repair,and at the end of the day you have piece of mind if ocean voyaging,the rudder has to work 24/7.............
__________________
my catamaran building project updates http://www.cruisersforum.com/forums/...36#post2502136
atoll is offline   Reply With Quote
Old 18-12-2011, 15:09   #7
Registered User

Join Date: Sep 2005
Boat: Nordhavn 50
Posts: 85
Re: rudder repair: kevlar??

Thanks guys for opinions,

Atoll- I see your point, altough I don't like to hear it ...thanks.

Shaft is fiberglass for shure. I'm not even certain there's any metal (tabs) inside. Core is definitely not soaked but there's definitely been water inside. But then again how many 10 years old rudder have absolutely no water in it.

I appreciate all your opinions, it's weighing in the balance.

Michel
__________________
siroismi is offline   Reply With Quote
Old 18-12-2011, 15:28   #8
Registered User

Join Date: Jan 2009
Location: Holland, France
Boat: 33ft sloop
Posts: 1,091
Images: 5
Re: rudder repair: kevlar??

I am sincerely shocked hearing the sums of money one has to pay for the privilege owning a boat in the US.
200 US$ for a day on the hard is totally unheard of. I pay such prices not even per month for a hard here in Holland. Also other indications show that boaters in the US are falling victim to a society of graverobbers. Now I understand the long distance haulages to get a boat on one' s own yard.

Atoll is more or less right and not less his statement that a rudder has to work 24/7.
Stay away from Kevlar. It is an unsuitable material, when in touch with moisture it loses half it's strength.
Use medium layers of E-glass or S-Glass and conform your rudder to a full laminate, skip any sandwich because it does not make any sense to save weight below the waterline.
A designers stupidity. Make sure that you align the two halves very well.
__________________
MacG is offline   Reply With Quote
Old 18-12-2011, 15:49   #9
Senior Cruiser
 
atoll's Avatar

Cruisers Forum Supporter

Join Date: Mar 2010
Location: gettin naughty on the beach in cornwall
Boat: 63 custom alloy sloop,macwester26,prout snowgoose 37 elite catamaran!
Posts: 9,312
Images: 75
Re: rudder repair: kevlar??

some photos would be great,is this a transome hung rudder? or conventional skeg and shaft.
so easy to make wrong assumptions due to quick descriptions of the problem!!!!
__________________
my catamaran building project updates http://www.cruisersforum.com/forums/...36#post2502136
atoll is offline   Reply With Quote
Old 18-12-2011, 18:24   #10
Registered User

Join Date: Sep 2005
Boat: Nordhavn 50
Posts: 85
Re: rudder repair: kevlar??

It is a spade rudder.

I finaly succeeded in uploading pics. I had to resize them myself.

You see a number of hole drilled to the core. The only wetness I've seen is what you see and also along the seam on leading edge.

Would you guys still split it open?

Michel
__________________
siroismi is offline   Reply With Quote
Old 18-12-2011, 18:30   #11
Registered User

Join Date: Mar 2009
Location: Sydney
Boat: Lexcen 40 - Leverage
Posts: 383
Re: rudder repair: kevlar??

Quote:
Originally Posted by MacG View Post
I am sincerely shocked hearing the sums of money one has to pay for the privilege owning a boat in the US.
200 US$ for a day on the hard is totally unheard of. I pay such prices not even per month for a hard here in Holland. Also other indications show that boaters in the US are falling victim to a society of graverobbers. Now I understand the long distance haulages to get a boat on one' s own yard.

Atoll is more or less right and not less his statement that a rudder has to work 24/7.
Stay away from Kevlar. It is an unsuitable material, when in touch with moisture it loses half it's strength.
Use medium layers of E-glass or S-Glass and conform your rudder to a full laminate, skip any sandwich because it does not make any sense to save weight below the waterline.
A designers stupidity. Make sure that you align the two halves very well.
Actually, this is Syney, Australia. The world's most expensive place. :\

I don't the those lucky Americans are paying this much!

As for aligning the halves - I wouldn't split it - leave enough in the leading and trailing edge and just rebuild the skin. It's not worth the effort in trying to keep the skins intact and taping over etc..
__________________
akio.kanemoto is offline   Reply With Quote
Old 18-12-2011, 18:33   #12
Registered User

Join Date: Mar 2009
Location: Sydney
Boat: Lexcen 40 - Leverage
Posts: 383
Re: rudder repair: kevlar??

Quote:
Originally Posted by siroismi View Post
It is a spade rudder.

I finaly succeeded in uploading pics. I had to resize them myself.

You see a number of hole drilled to the core. The only wetness I've seen is what you see and also along the seam on leading edge.

Would you guys still split it open?

Michel
There's no pic there, but it's like dropping the keel. Do you want peace of mind?

I dropped my keel and redid it for "warm fuzzy feelings" just so I could be sure that everythig was well...

So if you have any doubts, just cut the sides off the rudder, refoam, reglass per my instructions above.

Especially if you can work somewhere nice, it's not that hard or expensive. Took me three days, and 99% of that time was waiting for things to cure.
__________________
akio.kanemoto is offline   Reply With Quote
Old 18-12-2011, 18:34   #13
Registered User

Join Date: Feb 2009
Posts: 1,848
Re: rudder repair: kevlar??

how about this..... drill with a hole saw several 2'' inspection holes see what the inside looks like before you cut it in half maybe dig out foam and fill with resin and filer then glass the outside with cloth and expoy
__________________
motion30 is offline   Reply With Quote
Old 18-12-2011, 18:36   #14
Registered User

Join Date: Sep 2005
Boat: Nordhavn 50
Posts: 85
Re: rudder repair: kevlar??

Sorry, pics not attached to previous post
Attached Thumbnails
Click image for larger version

Name:	IMG_6620 copy.jpg
Views:	139
Size:	196.0 KB
ID:	34884   Click image for larger version

Name:	IMG_6621 copy.jpg
Views:	129
Size:	174.5 KB
ID:	34885  

Click image for larger version

Name:	IMG_6622 copy.jpg
Views:	122
Size:	370.8 KB
ID:	34886   Click image for larger version

Name:	IMG_6623 copy.jpg
Views:	138
Size:	166.1 KB
ID:	34887  

Click image for larger version

Name:	IMG_6624 copy.jpg
Views:	130
Size:	164.8 KB
ID:	34888  
__________________
siroismi is offline   Reply With Quote
Old 18-12-2011, 19:02   #15
Senior Cruiser
 
atoll's Avatar

Cruisers Forum Supporter

Join Date: Mar 2010
Location: gettin naughty on the beach in cornwall
Boat: 63 custom alloy sloop,macwester26,prout snowgoose 37 elite catamaran!
Posts: 9,312
Images: 75
Re: rudder repair: kevlar??

looking at the photo,and since it has a composite shaft that is probably epoxed to the outer moulding i would think that the chance of a catastrafic failure is very small even if the core was totally saturated.

i would recoat with epoxy and 250-350 gm matt ,fair ,prime ,anti- foul cant see there being an inherent pproblem unless there have been other documented failures of the main shaft.
__________________

__________________
my catamaran building project updates http://www.cruisersforum.com/forums/...36#post2502136
atoll is offline   Reply With Quote
Reply

Tags
repairs, rudder

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

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


Similar Threads
Thread Thread Starter Forum Replies Last Post
Rudder Skeg Mounting Repair Swift Drift Construction, Maintenance & Refit 9 06-11-2016 10:45
Rudder Repair on Prout Snowgoose tonydix Multihull Sailboats 7 31-01-2012 01:30
Crevice Corrosion - Is My Rudder Toast ? funjohnson Construction, Maintenance & Refit 41 14-11-2011 22:14
Yankee 28 Drew13440 Monohull Sailboats 34 13-10-2011 05:57
Dealing with a Soggy Cockpit Sole - The Story of My Repair Beersmith Construction, Maintenance & Refit 22 07-07-2011 12:17



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 19:17.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.