[Public-List] Bulkheads

Wes Gardner via Public-List public-list at lists.alberg30.org
Thu Feb 4 19:35:01 PST 2016


The only improvement I can see to do there is to make that inside radius between the knee and the inside of the hull a bit bigger.  Other than that, looks good! It can be a sticky mess!!

Sent from my iPad

> On Feb 4, 2016, at 10:25 PM, Hernán Scarnichia via Public-List <public-list at lists.alberg30.org> wrote:
> 
> picture of new knee: https://goo.gl/photos/38fxQRv566GU5HwN8
> 
> On Thu, Feb 4, 2016 at 6:24 PM, Hernán Scarnichia <hernanscar at gmail.com>
> wrote:
> 
>> Chip,
>> I just did exactly that on the forward lowers knees last weekend. cut
>> along the inboard edges and drilled out the rotten plywood, leaving part of
>> the tabbing in place to locate the new 3/4 G10 knees. as I removed the
>> plywood I was able to see how bad the tabbing had delaminated from the
>> hull. cleaned and sanded the inside of the old tabbing as much as I could
>> to get a better bond.
>> I sanded to bare fiberglass about 8 inches each side of the knee to bond
>> more tabbing. I cut into the flange/stringer holding the shelf to allow the
>> knees to extend below the shelf.
>> I used G-Flex toughened epoxy thickened with colloidal silica to bond the
>> new knee to the hull and 4 or 5 layers of 30oz cloth to tab into the hull
>> and to the shelf flange/stringer.
>> G10 is hard to cut, I used an angle grinder. I haven't tried drilling yet
>> but I suspect is not going to be easy.
>> I would suggest trying to align the new knees as best as you can with the
>> chainplate direction of pull, mine are not perfectly aligned and will make
>> it harder to install the chainplates, planning on adding some epoxy to get
>> a better angle.
>> here is a picture of the new G10 knee, not perfect but way stronger than
>> what was there.
>> 
>> On Thu, Feb 4, 2016 at 3:06 PM, Chip Dance via Public-List <
>> public-list at lists.alberg30.org> wrote:
>> 
>>> #456 has had the 5/16" bolt upgrade at some point by a PO, but she sat
>>> neglected for so long, much needs to be rebuilt/replaced, including the
>>> bulkheads (standing water up to the v-birth). I haven't test drilled the
>>> knees yet, but I would be very surprised if the plywood within is still of
>>> any use. However, the tabbing and glass around the knees still looks good.
>>> So I wonder if there is any advantage or concern with performing surgery
>>> on
>>> the knees? My thought is this:
>>> cut into the knee along the edge, gut out the plywood and replace with G10
>>> cut to fit the void and adhered with thickened epoxy or ??,  re-drill the
>>> bolt holes using the remaining for/aft parts of the knee as a guide,
>>> re-insert the chain plate, re-glass the edge of the knee and perhaps
>>> another layer or two over the entire knee and tabbing.
>>> The advantages I see in this refit process: re-using the original tabbing
>>> so you know the plates and knees are situated and adhered exactly as they
>>> were designed and built originally; eliminates the need to add new tabs (a
>>> concern for the neophyte); eliminates all concerns of future plywood rot
>>> (no plywood, no plywood rot). Of course maintaining a good seal around the
>>> chainplates would still be advisable, but not as critical as if the knees
>>> contained plywood.
>>> Keep in mind I am new at this, hence the sought advice, so I may not be
>>> thinking of everything.
>>> 
>>> Thoughts?
>>> 
>>> Chip
>>> #456
>>> 
>>> On Thu, Feb 4, 2016 at 4:23 PM, Gordon Laco via Public-List <
>>> public-list at lists.alberg30.org> wrote:
>>> 
>>>> Hello Stephen,
>>>> 
>>>> I was a great believer in SikaFlex in my wooden boat days, but have
>>> turned
>>>> back to Boatlife 'Lifecaulk' for Surprise.  I think it adheres better to
>>>> fibreglass than SikaFlex (but not too well as with 5200)
>>>> 
>>>> I've never come across a non-curing butyl but do recall the stuff
>>>> originally
>>>> used in our boats was something similar.
>>>> 
>>>> Gord #426 Surprise
>>>> 
>>>> 
>>>> On 2016-02-04, 5:54 PM, "Stephen Gwyn via Public-List"
>>>> <public-list at lists.alberg30.org> wrote:
>>>> 
>>>>> 
>>>>> So what are people's favourite sealant? I've been using
>>>>> BoatLife polysulfide sealant. Polyurethane  (3M5200 and Sikaflex)
>>>>> is too permanent. Silicone is permanent enough and once you
>>>>> use it, nothing will stick to where it has been.
>>>>> 
>>>>> I was reading a british sailing, which recommended a butyl sealant
>>>>> which stayed sticky indefinitely, meaning that when the seal flexed
>>>>> and split, it would just seal itself again.
>>>>> 
>>>>> Thoughts?
>>>>> 
>>>>> SG
>>>>> 
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