Cruisers Forum
 


Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on Cruisers Forums. Advertise Here
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 27-11-2020, 14:36   #1
Registered User

Join Date: Sep 2009
Posts: 511
Rudder repair - should I taper the core?

Would u suggest Im tapering the core? If so how much and with a 45 degree cut or a 50% deep 90 degree cut?

Or other suggestion that would help


Thanks
Attached Thumbnails
Click image for larger version

Name:	20201127_152805.jpg
Views:	126
Size:	417.8 KB
ID:	227757  
andreas.mehlin is offline   Reply With Quote
Old 27-11-2020, 15:42   #2
Registered User

Join Date: Feb 2018
Posts: 1,301
Re: Rudder repair - should I taper the core?

I suggest refining your question a bit (I'm curious about the answer).

Are you meaning tapering the aft edge of the forward core...like a scarf joint? What kind of boat is this from?

What is your layup schedule to be? How many layers of what ounce what? Will this layup fully envelope the rudder, or are you just laying up one side? Any idea on the skins on their in the first place?
Singularity is offline   Reply With Quote
Old 27-11-2020, 16:05   #3
Registered User

Join Date: Sep 2009
Posts: 511
Re: Rudder repair - should I taper the core?

Since before it's abot 2-3mm fiberglass.
Although there is about 5-6 mm gelcoat/fairing compund....so I could go thicker on with fiberglass.

Only planning to lay up this side. With about 1-1 1/2 of solid fiberglass on the trailing edge. Will be using epoxy.



Boat 46ft trimaran
andreas.mehlin is offline   Reply With Quote
Old 27-11-2020, 16:11   #4
Registered User
 
Bill O's Avatar

Join Date: Jul 2015
Boat: Bruce Bingham Christina 49
Posts: 1,864
Re: Rudder repair - should I taper the core?

What are you trying to do here, change the overall rudder shape? What foil type was it before?
__________________
Bill O.
KB3YMH
https://phoenixketch.blogspot.com/
Bill O is offline   Reply With Quote
Old 27-11-2020, 16:52   #5
Registered User

Join Date: Jan 2018
Boat: 50ft Custom Fast Catamaran
Posts: 4,220
Re: Rudder repair - should I taper the core?

Why not just make the core the same taper as the bottom (deepest) part of the rudder? Ie: make the core the proper shape of the foil.

Then put the normal amount of glass on all the way through the whole rudder.

It’ll save weight and be easier than trying to fair the outside.
Chotu is online now   Reply With Quote
Old 27-11-2020, 21:55   #6
Registered User

Join Date: Sep 2009
Posts: 511
Re: Rudder repair - should I taper the core?

Quote:
Originally Posted by Bill O View Post
What are you trying to do here, change the overall rudder shape? What foil type was it before?
haha, sorry...I forgot to say.
It had rotton core, so I cut out the rot and the damp core.

...Im just looking to replace what I have taken out.
andreas.mehlin is offline   Reply With Quote
Old 27-11-2020, 21:59   #7
Registered User

Join Date: Mar 2011
Location: Southport CT
Boat: J/36
Posts: 1,571
Re: Rudder repair - should I taper the core?

What Chotu said.
psk125 is offline   Reply With Quote
Old 27-11-2020, 22:09   #8
Registered User

Join Date: Sep 2009
Posts: 511
Re: Rudder repair - should I taper the core?

Quote:
Originally Posted by Chotu View Post
Why not just make the core the same taper as the bottom (deepest) part of the rudder? Ie: make the core the proper shape of the foil.

Then put the normal amount of glass on all the way through the whole rudder.

It’ll save weight and be easier than trying to fair the outside.
I think you misunderstood me...and maybe because I used the word "taper" wrong. What I mean is how to make the joint between the new and old core. Scarf joint or just put in the new core in the pocket as it is now.
andreas.mehlin is offline   Reply With Quote
Old 27-11-2020, 22:34   #9
Registered User

Join Date: Nov 2019
Location: Gold Coast, Australia
Boat: Farr 43`
Posts: 168
Re: Rudder repair - should I taper the core?

Scarf

See if you can find something better than wood as core material.
Rucksta is online now   Reply With Quote
Old 27-11-2020, 22:49   #10
Registered User

Join Date: Sep 2009
Posts: 511
Re: Rudder repair - should I taper the core?

Quote:
Originally Posted by Rucksta View Post
Scarf

See if you can find something better than wood as core material.
Problem is getting it here in Mexico. Shipping foam sheet from the states down here is sort of impractical.

How about strip planking and coating each strip with epoxy? Water shouldn't be any issues at least?
andreas.mehlin is offline   Reply With Quote
Old 28-11-2020, 02:11   #11
Registered User

Join Date: Nov 2019
Location: Gold Coast, Australia
Boat: Farr 43`
Posts: 168
Re: Rudder repair - should I taper the core?

Quote:
Originally Posted by andreas.mehlin View Post
Problem is getting it here in Mexico. Shipping foam sheet from the states down here is sort of impractical.

How about strip planking and coating each strip with epoxy? Water shouldn't be any issues at least?
You could try and find a door with a cardboard honeycomb core.
Strip the skins and remove the core.

The following steps describe how to make ghetto Nomex.

The honeycomb will be too coarse to take the compression loads encountered on the trailing edge of a rudder.
Cut the core to the shape of your project with a box knife.
Test fit - it will be nice and flexible.
Cut somewhat circular plugs from the excess core and spiral them into alternate holes in the core as a test fit.
Remove the plugs.
Apply a slurry of thickened epoxy (glue ) to the work area on the rudder.
Allow epoxy to get sticky.
Apply honeycomb to rudder.
Use masking tape to hold in place.
Allow epoxy to set - no need to wait for cure.
Remove tape.
Spray coat of epoxy over and into the honeycomb.
Insert plugs whilst epoxy is wet
Spray another coat of epoxy over the combined core material.
Allow to set
Clean up knock off and have a beer while the sun goes down.

Fair to final shape.
Cut a layer of non emulsion Chopped Strand Mat to fit.
Wet out the CSM and allow to gel (sticky)
Apply CSM to work
Allow to set (not cure)
Apply thickened epoxy (glue) to CSM
Allow to Gel
Apply on a layer of laminating resin.
Apply bi directional cloth , roll , add resin
Repeat.
Allow to gel
Fair


Job done by beer thirty on day two ready for final sand barrier coat and antifoul on the same schedule as the rest of the hull/appendages.

Best not to use 5:1 or 7:1 resins.
4:1 is OK but 2:1 is best for non blush formulations that allow the work flow to continue without curing and sanding.

If you are stuck with a blushing resin (West?) brown vinegar will remove the blush at any stage from gel to cure without sanding.

Strip planking would take me 3-4 days.
Expanding foam about a day and a half.
Rucksta is online now   Reply With Quote
Old 28-11-2020, 02:20   #12
Registered User

Join Date: Jan 2018
Boat: 50ft Custom Fast Catamaran
Posts: 4,220
Re: Rudder repair - should I taper the core?

Quote:
Originally Posted by andreas.mehlin View Post
I think you misunderstood me...and maybe because I used the word "taper" wrong. What I mean is how to make the joint between the new and old core. Scarf joint or just put in the new core in the pocket as it is now.
Oh!!!

Now it all makes sense.

Id do a scarf joint. Taper as large as you can possibly do. Bond with epoxy.

It is not the best rudder for your trimaran with a wood core, but I read your other posts and I understand the options for a core are limited. Foam is, of course, best. But I see it is not available where you are.
Chotu is online now   Reply With Quote
Old 28-11-2020, 02:24   #13
Senior Cruiser
 
GordMay's Avatar

Cruisers Forum Supporter

Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Posts: 39,779
Images: 241
Re: Rudder repair - should I taper the core?

Quote:
Originally Posted by andreas.mehlin View Post
... How about strip planking and coating each strip with epoxy? Water shouldn't be any issues at least?
Do I understand correctly, that you’re (partially) replacing a rotten core, but don’t think water might be a problem?
__________________
Gord May
"If you didn't have the time or money to do it right in the first place, when will you get the time/$ to fix it?"



GordMay is offline   Reply With Quote
Old 28-11-2020, 05:22   #14
Registered User

Join Date: Sep 2009
Posts: 511
Re: Rudder repair - should I taper the core?

Quote:
Originally Posted by Chotu View Post
Oh!!!

Now it all makes sense.

Id do a scarf joint. Taper as large as you can possibly do. Bond with epoxy.

It is not the best rudder for your trimaran with a wood core, but I read your other posts and I understand the options for a core are limited. Foam is, of course, best. But I see it is not available where you are.
If you would have chosen. What material would u have used? Expandable foam?
andreas.mehlin is offline   Reply With Quote
Old 28-11-2020, 05:32   #15
Registered User
 
Sherpa17's Avatar

Join Date: Jun 2019
Posts: 106
Re: Rudder repair - should I taper the core?

Does it need a core? Could you lay it up?
Sherpa17 is offline   Reply With Quote
Reply

Tags
core, rudder

Thread Tools Search this Thread
Search this Thread:

Advanced Search
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
Prop shaft and taper details for a Jeanneau 43ds SaltyMetals Propellers & Drive Systems 7 14-12-2017 00:34
Want To Buy: Heel taper thall52 General Classifieds (no boats) 2 12-10-2016 04:50
Stainless Rudder Stock Needs Replacing In Foam Core Rudder? dennisail Construction, Maintenance & Refit 35 07-09-2016 16:55
steering wheel shaft taper damianham Construction, Maintenance & Refit 2 02-02-2015 03:20
Is this what They Mean when They Say to Taper the Hole ? off-the-grid Construction, Maintenance & Refit 11 18-05-2010 15:29

Advertise Here


All times are GMT -7. The time now is 16:45.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2021, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2021, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.