Martxer
Active member
Some of the sealant around the hull windows has split in places and falling out in others.
What is recommended to replace the sealant?
Thanks
What is recommended to replace the sealant?
Thanks
Hull windows
- Thread starter Martxer
- Start date
stelican
Well-known member
Probably best to ask builder as you may find that additional sealant may interact.
jfm
Well-known member
Depends whether you're dealing with bonded windows, or mechanically clamped windows where the sealant acts only as sealant and not as adhesive
Martxer
Active member
I would hazard a guess that the windows are bonded and the sealant is just a sealant. I would be really worried if this stuff is adhesive.
jfm
Well-known member
Did you mean to say "bonded"? Or did you mean "bolted"?
Martxer
Active member
Bonded.
I have asked the dealer to clarify.
I have asked the dealer to clarify.
jfm
Well-known member
OK. Must admit I'm confused. If the windows are "bonded" that normally means the sealer also serves as an adhesive, but you're suggesting it doesn't.
You can tell the difference just by looking at the windows (or telling us the make/model of the boat)
Reason for me asking this whole question is that the choice of glue to suggest you use depends on whether it is serving as just a sealant or as an adhesive too.
You can tell the difference just by looking at the windows (or telling us the make/model of the boat)
Reason for me asking this whole question is that the choice of glue to suggest you use depends on whether it is serving as just a sealant or as an adhesive too.
Plum
Well-known member
If the glazing is bonded then there is no reason for sealant as well unless someone has added the sealant in service because of a failure of the bond.
Martxer
Active member
Boat is a merry fisher 895 hull windows come in 2 peices and look like they would be bonded.
I would then assume the sealant on the outside is to tidy things up.
I would then assume the sealant on the outside is to tidy things up.
Martxer
Active member
Sealant is used widely in construction not to bond 2 items but to tidy up the finish or in the case of window frames stop water ingress
jfm
Well-known member
Merry fisher 895 clearly has what I would call bonded windows in its hull sides. That is, windows where the glass is glued to a flange in the GRP mounding, and a single polyurethane product serves as both adhesive and sealant. I'm still confused though, because OP is referring to "two pieces" and I don't know what the second piece is, and also OP is suggesting that the sealant isn't the adhesive, which might be true but it makes no sense to me in this scenario.
I'm happy to suggest products for bonding or sealing, but will keep away while the facts are confusing (to me at least!).
I'm happy to suggest products for bonding or sealing, but will keep away while the facts are confusing (to me at least!).
Martxer
Active member
jfm
Well-known member
Ah ok thanks.
The "two pieces" thing is a red herring.
That looks like fritted glass (ceramic printed fritting) and will be bonded onto the GRP flange using a polymer/polyurethane. My weapon of choice for fixing the glass onto such a GRP flange would be Sabatack 750xl (with primer 9910 on the gelcoat), but there are plenty of competitor products. Sabatack has been used by many boatbuilders and I have owned boats for 10 years from new with this product, and had zero problems, in sunny climates (Med).
As for trimming/sealing, as distinct from adhesion, I would use the same product and I believe most builders do, where it is needed (it usually isn't). I have had Sabatack exposed to sun on a slanting transom window, with a 4mm fillet of Sabatack around the edge of the glass exposed to the sun for 9 years with zero problems.
However, it looks from your photo that, consistent with how most builders do it, there is no sealing fillet along the horizontal top/bottom edges of the glass. Instead. it looks to me like there is a just an adhesion bead of glue that is mostly protected from the sun by the fritting and by being in a recess, but the top edge of the glue bead gets some sun. That product will be an adhesive not a mere sealant and I would use Sabatack for patching that.
In contrast, if you wanted only to repair a sun-exposed vertical sealing line between the two pieces of glass where they abut, then any black polyurethane would also be fine for example Sika 295UV or 291iUV
The "two pieces" thing is a red herring.
That looks like fritted glass (ceramic printed fritting) and will be bonded onto the GRP flange using a polymer/polyurethane. My weapon of choice for fixing the glass onto such a GRP flange would be Sabatack 750xl (with primer 9910 on the gelcoat), but there are plenty of competitor products. Sabatack has been used by many boatbuilders and I have owned boats for 10 years from new with this product, and had zero problems, in sunny climates (Med).
As for trimming/sealing, as distinct from adhesion, I would use the same product and I believe most builders do, where it is needed (it usually isn't). I have had Sabatack exposed to sun on a slanting transom window, with a 4mm fillet of Sabatack around the edge of the glass exposed to the sun for 9 years with zero problems.
However, it looks from your photo that, consistent with how most builders do it, there is no sealing fillet along the horizontal top/bottom edges of the glass. Instead. it looks to me like there is a just an adhesion bead of glue that is mostly protected from the sun by the fritting and by being in a recess, but the top edge of the glue bead gets some sun. That product will be an adhesive not a mere sealant and I would use Sabatack for patching that.
In contrast, if you wanted only to repair a sun-exposed vertical sealing line between the two pieces of glass where they abut, then any black polyurethane would also be fine for example Sika 295UV or 291iUV
Martxer
Active member
Thanks jmf the vertical joint between the 2 the sealant is coming out and needs replacing, the horizontal seal on the top of the glass has a small split in it.I will re seal the vertical joint with the sika 295 or 291 and monitor the horizontal seal .
jfm
Well-known member
Sounds good to me 
