Don,
I have had a close look, and submitted a brief write up for the next newsletter.
My findings, specific to Superseal 26/84 1980 John Baker built:-
The rudder is constructed from two halves laid up in grp.
The two halves do not match, and filler has been applied externally to fair the mismatch; this was poorly bonded.
The joint all round the blade was filled with what appears to be car body filler.
The interior has a (two??)steel reinforcments and has a high density filler, which is porous.
The rudder is extremely heavy.
Two "U" shaped s/s brackets were bolted to the rear of the stock indicating that the joint had opened.
The view of the surveyor was that this appeared to be an adequate repair
I discovered cracks after removing the pintle fittings and the antifouling.
THEY WOULD NOT BE VISIBLE EVEN TO CLOSE INSPECTION WITH THE RUDDER MOUNTED.
On stsrting to repair, i.e. grind out the laminate to remove the cracks it seems that the laminate in the area of the pintles is resin rich i.e. not enough glass.
The glass was only chopped strand mat.
As any rudder is subject to bending loads I would have expected a laminate with alternate layers of chopped/woven rovings or even unidirectional.
Woven rovings 2 times strength unidirectional 4 times.
At this point I decided to cut core samples with a hole drill further down the blade.
This yielded a saturated core and some not-fully-wetted out grp.
At this point I decided that the rudder was scrap, and that all Superseal fixed rudders were suspect and should be examined immediately
Subsequently I have removed more of the filler round the steel reinforcment, which is drilled for the pintle bracket front bolt, and the steel is also cracked.
I am begining to think that the problem is caused more by the weight of the rudder rather than the steering loads.
Frank Marsden
Frank Marsden