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 29-01-2017, 22:20   #1
Registered User
 
first wind's Avatar

Join Date: Nov 2013
Location: Chesapeake bay area
Boat: 1971 cal 27
Posts: 427
Skeg construction

hi. i am in the middle of refitting a 1971 cal 27 pop top. one thing i do not like about the boat, that i am having difficulties finding out how to change, is the spade rudder. i would feel much better if it was skeg hung.

in theory, that shouldn't be hard to achieve. build another rudder...that part there is a ton of info on the web about...and build and attach the skeg....that part, no matter how hard i look, i can't find out anything about. so, here i am.

i have read that skegs are very hard to do as a part of a one piece mold and that many companies add the skeg afterwards. so, here are my questions:

on a solid hull boat (as compared to a cored boat) how is the skeg built? is it cored, solid, or hollow?

secondly, how s it attached? by this i mean how is it glassed on? i guess to explain, it's like this: if you plug a thru hull you glass on the inside and outside. the hull around the hull has to be tapered back inside and outside 12X the thickness of the hull. so, if your hull was half an inch thick, each side would have to be tapered back 3". that's the proper way to glass a through hull shut. so, with that in mind how do they glass the skeg onto the finished hull?

any information would be a big help. it really shouldn't be that terrible a job but, finding out any information on how to do it is neigh on impossible.

thanks
__________________
we go wherever we want to go. that's what a ship is, you know. it's not just a keel and a hull and a deck and sails. that's what a ship needs. but what a ship is...really is...is freedom---captain jack sparrow
first wind is offline   Reply With Quote
Old 30-01-2017, 06:06   #2
Registered User

Join Date: Aug 2009
Location: between the devil and the deep blue sea
Boat: a sailing boat
Posts: 20,409
Re: skeg construction

I have seen skegs both molded and added on. The added on were added in the production process, not post production (grp boats).

The ones I have seen were some solid some filled with foam. The full long ones were (foam ?) filled. Half skegs on some quality scandinavian designs were solid grp. Heavy but strong.

I would not add a skeg to any design that has a spade rudder. This changes the hydro of the hull and can create more trouble than benefit.

Buy a new rudder, replace the bearings and (optionally) strengthen the bearing/tube area.

A well designed and build spade is as strong as anything else.

b.
barnakiel is offline   Reply With Quote
Old 30-01-2017, 06:07   #3
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: 47,076
Images: 241
Re: skeg construction

Here's one example ➥ WEST SYSTEM | Skeg Construction For Sparks
__________________
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 30-01-2017, 06:12   #4
Registered User
 
neilpride's Avatar

Join Date: Jul 2009
Location: in the world
Boat: csy 44 tall rig.
Posts: 3,108
Re: skeg construction

Most skegs i see in my life are Split in half in the intial hull construction , that mean 2 halfs joined together and FG tabed inside, later filled with a mush of resin and FG the top, filled with foam and in some cheaps boats with crap,, and agree with Barnakiel if is a spade rudder keep it like that ... there is a bunch of ways to improve a existing spade rudder....Cheers.
neilpride is offline   Reply With Quote
Old 30-01-2017, 07:06   #5
Moderator
 
noelex 77's Avatar

Cruisers Forum Supporter

Join Date: Jul 2007
Boat: Bestevaer.
Posts: 13,355
Re: skeg construction

Bob Perry once suggested many skegs are held on by the rudder, not the other way around .

I think you are going to find it hard to easily retrofit something strong. If the skeg is deformed it will likely jam the rudder so you will need to be careful that you will not put in a lot of work and end up with something worse, especially when the other drawbacks of a skeg rudder are considered.
noelex 77 is offline   Reply With Quote
Old 30-01-2017, 07:24   #6
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: 47,076
Images: 241
Re: skeg construction

Quote:
Originally Posted by noelex 77 View Post
Bob Perry once suggested many skegs are held on by the rudder, not the other way around ...
Indeed.
“... For me, a spade rudder should be engineered to be just as strong as a skeg-hung rudder. A good knock at the heel fitting of a skeg-hung rudder can easily jam the stock up into the hull, causing damage. The common geometry of most skegs make them very difficult to laminate and I am very confident that there are a lot of skegs out there being held on by the rudders ...”
From A Bob Perry Design Review ➥ Perry Design Review: Morris 32 - boats.com
__________________
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 30-01-2017, 08:04   #7
Registered User
 
goat's Avatar

Join Date: Apr 2013
Location: Everywhere (Sea of Cortez right now)
Boat: PSC Orion 27
Posts: 1,366
Re: skeg construction

Quote:
Originally Posted by first wind View Post
hi. i am in the middle of refitting a 1971 cal 27 pop top. one thing i do not like about the boat, that i am having difficulties finding out how to change, is the spade rudder. i would feel much better if it was skeg hung.

in theory, that shouldn't be hard to achieve. build another rudder...that part there is a ton of info on the web about...and build and attach the skeg....that part, no matter how hard i look, i can't find out anything about. so, here i am.

i have read that skegs are very hard to do as a part of a one piece mold and that many companies add the skeg afterwards. so, here are my questions:

on a solid hull boat (as compared to a cored boat) how is the skeg built? is it cored, solid, or hollow?

secondly, how s it attached? by this i mean how is it glassed on? i guess to explain, it's like this: if you plug a thru hull you glass on the inside and outside. the hull around the hull has to be tapered back inside and outside 12X the thickness of the hull. so, if your hull was half an inch thick, each side would have to be tapered back 3". that's the proper way to glass a through hull shut. so, with that in mind how do they glass the skeg onto the finished hull?

any information would be a big help. it really shouldn't be that terrible a job but, finding out any information on how to do it is neigh on impossible.

thanks
In the last 47 years of your boat's life, how often was the spade rudder lost? If the answer is zero, I'd look for other things to worry about.

goat
goat is offline   Reply With Quote
Old 30-01-2017, 09:32   #8
Moderator Emeritus
 
a64pilot's Avatar

Cruisers Forum Supporter

Join Date: Oct 2013
Location: Jacksonville/ out cruising
Boat: Island Packet 38
Posts: 31,351
Re: skeg construction

Would it not be very likely that you would lose quite a lot of maneuverability?
And as how spade rudders are usually balanced as in they have a lot of surface area ahead of the pivot point, are you not likely to end up with a very hard steering boat?

Likely best to sell this boat and buy one that has a skeg rudder?
a64pilot is offline   Reply With Quote
Old 30-01-2017, 09:43   #9
Registered User
 
Suijin's Avatar

Join Date: Feb 2013
Location: Bumping around the Caribbean
Boat: Valiant 40
Posts: 4,626
Re: skeg construction

You're going to have to redesign the whole rudder on that boat to hang it with a skeg. Not only is it currently swept, but the pivot is not vertical. It's going to change how the boat handles, and you'll be adding a bit of weight that the boat was not designed for.

If you're cruising in the Chesapeake I don't understand why you'd be so set on a skeg hung rudder anyway. The keel on that boat is considerably deeper than the rudder, and the Bay is not exactly filled with rocks.

It's one thing if you're headed way offshore, then there would be an argument to be made about it's benefits (and it would be an argument, as there are lots who believe otherwise, with valid reasons). But you're not. I doubt you'll ever be out of VHF/SeaTow range in that boat so why go spending hundreds of dollars and hours adding something you'll probably never need and which will alter the boat's already fine sailing characteristics?
Suijin is offline   Reply With Quote
Old 30-01-2017, 10:41   #10
Marine Service Provider

Join Date: May 2012
Location: New Orleans
Boat: We have a problem... A serious addiction issue.
Posts: 3,974
Re: skeg construction

So I wrote out a long post on how to get started, but really the only way Tom convert from a spade to a skeg and do it right is to cut off everything you have and go to a designer and have them design you something. Then build and install whatever they suggest. It's a massive addition involving removing a lot of glass from the hull to bond the new skeg to, likely installing a new skeg sump and bolts in the boat, a completely new rudder, and a lot of engineering that is beyond my ability.

All of this will gain you absolutly nothing btw. The boat will be slower, no more safe, and the rudder just as prone to damage as before, it just changes the failure method. If you really have doubts about the rudder strength then ask a NA to design a stronger rudder for you and shop it out to Phils Foils. For a couple of grand you can drop in a newlyweds designed rudder that is X amount stronger than what you have. X being whatever number makes you feel good. Because if a rudder has lived for 45+ years it was probably engineered right the first time.
__________________
Greg

- If animals weren't meant to be eaten then they wouldn't be made of food.
Stumble is offline   Reply With Quote
Old 30-01-2017, 10:47   #11
Moderator
 
noelex 77's Avatar

Cruisers Forum Supporter

Join Date: Jul 2007
Boat: Bestevaer.
Posts: 13,355
Re: skeg construction

Quote:
Originally Posted by GordMay View Post
I am very confident that there are a lot of skegs out there being held on by the rudders
Thanks for finding the exact quote Gord .
noelex 77 is offline   Reply With Quote
Old 30-01-2017, 13:47   #12
Registered User

Join Date: Jul 2005
Location: Bellingham
Boat: Outbound 44
Posts: 9,314
Re: skeg construction

Lots of work for less than no gain.
__________________
Paul
Paul L is offline   Reply With Quote
Old 30-01-2017, 22:47   #13
Registered User
 
first wind's Avatar

Join Date: Nov 2013
Location: Chesapeake bay area
Boat: 1971 cal 27
Posts: 427
Re: skeg construction

in response, in another interview, Bob Perry states he thinks the best compromise is a rudder with a short skeg as this allows a bit of rudder before the pivot point and keeps the bearing away from the very bottom of the rudder where it is likely to get struck.

everyone who likes spade rudders swears they are as safe as skeg hung rudders. it's kind of like everyone that loves fin keels swears they are just as seaworthy as full keel boats ( a point that C.A. Marchaj's book on seaworthiness totally debunks).

spade rudders do break off and they do fall off. they are supposed to be designed to break off before they crowbar a huge hole in the hull. make one strong enough not to break off and you eradicate the designed in failure point. it would be like running electricity without a breaker or a fuse.

yes, if i never leave the bay i will be within a call away if it does break off and then i can figure out how to pay for the tow-in. as far as the bay having a soft bottom, spade rudders are vulnerable to other things besides groundings. logs and other unseen obstructions can damage them, too.

i realize i would have to make a completely different rudder. i believe i included that in my original post.

boats have been sailing for a long time without spade rudders. skeg hung rudders and even full keel vessels have maneuverability to sail. the biggest loss in maneuverability is backing under power, maneuvering around the marina, or racing around the buoys. i intend to cruise not race. i chose my slip at the marina just for it's ease of setting off and returning. i won't have to be maneuvering around a tight marina all the time. if you talk to cruisers with skeg hung rudders, you don't here a lot of depressed sailors trapped with a boat that just won't steer.

i don't see the skeg as being a useless thing that won't add rudder protection. there are enough people out there whose skegs took a grounding and protected the rudder for me to believe they do work. just like there are more than enough spade rudder failures for me to believe they are not as safe/strong as a skeg hung rudder. just because some people make it over Niagara Falls in a barrel and live, that doesn't mean that's a safe mode of transportation over the falls. plenty of other people in barrels didn't make it.

finally, thanks for posting the link to that article. i have actually seen that. the problem is that it doesn't go into detail about attaching the skeg and i doubt that skeg is under the same stresses as one on a sailboat. but, i do appreciate you trying to answer the question i asked.
__________________
we go wherever we want to go. that's what a ship is, you know. it's not just a keel and a hull and a deck and sails. that's what a ship needs. but what a ship is...really is...is freedom---captain jack sparrow
first wind is offline   Reply With Quote
Old 30-01-2017, 22:55   #14
Registered User
 
first wind's Avatar

Join Date: Nov 2013
Location: Chesapeake bay area
Boat: 1971 cal 27
Posts: 427
Re: skeg construction

Quote:
Originally Posted by Stumble View Post
Because if a rudder has lived for 45+ years it was probably engineered right the first time.
i am not doubting that Lapworth designed the rudder well, for it's intended purpose. however one point about the above statement:

the brass gate valves the boat was built with, instead of bronze seacocks, have held up for 45+ years. perhaps brass gate valves are just as good for the purpose as bronze seacocks. not trying to be a butthole. just pointing out the flaw in that logic.

(and, no, i'm not leaving the gate valves in place. i'm actually glassing over all of the thru hulls as the only one i might have used would be the one for the galley sink but, there are better ways to handle the sink than to have a hole in the bottom of your boat. my relationship with murphy being what it is, i try to leave less to go wrong, if i can.)
__________________
we go wherever we want to go. that's what a ship is, you know. it's not just a keel and a hull and a deck and sails. that's what a ship needs. but what a ship is...really is...is freedom---captain jack sparrow
first wind is offline   Reply With Quote
Old 31-01-2017, 00:49   #15
Marine Service Provider

Join Date: May 2012
Location: New Orleans
Boat: We have a problem... A serious addiction issue.
Posts: 3,974
Re: skeg construction

In that case you need to hire a NA to design a new rudder and skeg. Figure you will need to remove 2 or 3 layers of glass within a foot or so of the new rudder post in order to bond the new skeg on, and likely reinforce the inside of the hull where the new skeg will be located.

The upside is you can likely go to a much thinner rudder post since the skeg will be carrying part of the load so you won't need the post to be as stiff.
__________________
Greg

- If animals weren't meant to be eaten then they wouldn't be made of food.
Stumble is offline   Reply With Quote
Reply

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
Is a Skeg Necessary without an Inboard and with a Transom-Hung Rudder ? BudgieSmuggler Monohull Sailboats 27 21-03-2011 05:43
Sailing Qualities of Full Keel vs Fin Skeg . . . otherthan Monohull Sailboats 17 12-03-2011 04:28
Skeg-Mounted Rudders SailBR Monohull Sailboats 9 18-09-2009 05:53
Gulfstar 37 skeg backing plate corrosion jlogan Construction, Maintenance & Refit 1 11-08-2008 16:24
Skeg hung rudder kingfish Construction, Maintenance & Refit 3 20-07-2005 12:12

Advertise Here


All times are GMT -7. The time now is 18:12.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2022, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2022, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.