Thru hull removal

[firstbase]

Had the yard remove an old seacock and thru hull. Watched them complete the exterior and all seemed well. Then...the interior....this can't possible be correct. See pics. Don't you normally glass the inside?

 

[High Wire]

Is that the bottom or the side?

 

[firstbase]

Pictures taken from inside the engine room. Thru hull was on the bottom of the boat about 3' off the centerline towards the stern. Maybe 1/3 of length of the boat forward of the stern. Just never heard of glassing a hole in a hull from one side only.

 

[boomerang]

It looks like they just put a patch on the outside & from what I can see , a grinder never came near the hole! I would respectfully ask the yard to repair it correctly.

 

[BruceK]

You are deleting the through hull?
I`d expect the hole to be filled with mat and epoxy to produce a flat surface both sides, making the hull as it was before the hole was ever cut.
I had one removed recently. A wood block was placed over the inside of the repair.

 

[Lou_tribal]

What is the thickness of the hull at that place?
I agree that for the finishing inside they should have feathered this but it may be just a finition matter more than a structural matter.

L

 

[dhmeissner]

https://youtu.be/MVLRjxe_iUw

 

[boomerang]

Rather than simply filling it, which isn't a strong repair at all, it should've been feathered on both sides & filled with successive layers of glass until the original thickness is obtained. I wouldn't be happy with that "repair"!

 

[SoWhat]

Rather than simply filling it, which isn't a strong repair at all, it should've been feathered on both sides & filled with successive layers of glass until the original thickness is obtained. I wouldn't be happy with that "repair"!

Agree. That is not a repair. Probably a good idea to discuss the plan on correcting it with the boatyard. Get some specifics on how many layers of mat they plan on using, size of each layer, what type of epoxy, etc.

 

[Comodave]

It needs to be feathered to a 12:1 ratio, that is if the hull is .25” then the feathering needs to be a minimum of 3” diameter on both sides of the hull. Then glassed to fill the hole on both sides.

 

[Art]

https://youtu.be/MVLRjxe_iUw

Thanks! Dave


https://youtu.be/MVLRjxe_iUw

 

[firstbase]

I watched the exterior repair and talked to the guy while he did it so I could learn a little in real life. Feathered the hole, used increasing size circles of mat not directly overlapping, etc. Barrier coat over it all and then bottom paint of course. Stupid me, I had a dozen projects going on, got wrapped up with them and just forgot to get in there and inspect the "finished" job. I email the yard and will see. respected yard and guy, been there 30 some years. I don't have much doubt he will make it right. Will see though.

 

[Cigatoo]

I watched the exterior repair and talked to the guy while he did it so I could learn a little in real life. Feathered the hole, used increasing size circles of mat not directly overlapping, etc. Barrier coat over it all and then bottom paint of course. Stupid me, I had a dozen projects going on, got wrapped up with them and just forgot to get in there and inspect the "finished" job. I email the yard and will see. respected yard and guy, been there 30 some years. I don't have much doubt he will make it right. Will see though.

Sounds like done right. Just needs some putty on the back side. Aesthetic reasons mostly.

 

[psneeld]

One sided repairs can be done but usually for large areas, not a small hole as it is easier to do both sides as long as you have good access.

Just a guess based on the photos, but this looks like it needs to be finished on the inside to complete the repair at least. It would also make it nice looking to boot.

Upon looking at the photos again.... not sure the guy finished the job.

Looks like he started the inside and stopped before finishing the grinding and glass repair. Not unheard of in marina work.

 

[High Wire]

The inside looks like exposed plywood core. Is that wood?

 

[firstbase]

No, that's just stain from a poorly glassed in backing plate that was removed. It is a solid fiberglass hull.

What type of fiberglass mat/tape is appropriate to finish this side? should it be 1808 bi-axial and all that or simple chopped strand?

 

[psneeld]

I would grind my interior bevel, and use roving like is in the hull.

Can get it just about anyplace.

No need to get tech for this, but chopped strand I am not a fan of.

 

[firstbase]

Thanks PS. Was looking for some online and can't find much in small amounts. 1 yard would be more than enough. Lots of 2" and 4" tape, and I would need 8" across or so for the first layer. I believe it should be one piece to be correct and not two 4" pieces. Maybe I'm making too much of the repair finishing. This is all for if I do it myself, the yard my make it right. Just don't know if I want to go through the hassle for what appears to be a simple 30 minute job.

 

[HopCar]

I watched the exterior repair and talked to the guy while he did it so I could learn a little in real life. Feathered the hole, used increasing size circles of mat not directly overlapping, etc. Barrier coat over it all and then bottom paint of course. Stupid me, I had a dozen projects going on, got wrapped up with them and just forgot to get in there and inspect the "finished" job. I email the yard and will see. respected yard and guy, been there 30 some years. I don't have much doubt he will make it right. Will see though.

From your description it sounds like he did it right. Looking at the photos, it looks like he didn't feather it enough. The hole should be completely full of glass.
All the work is done from the outside. A temporary backing is attached inside to support the patch until itardens.

There are several good videos on You Tube. This is a pretty good one.

Note that the smallest circle of glass should go on first. The video doesn't make that clear.

 

[TDunn]

Looks like they did half the repair. To finish, grind a bevel on the inside and fill with proper fabric (NOT MAT). The 1808 you mentioned will work very well. Rotate pieces so the strands do not line up with the piece below. Woven roving is old tech which I would not use.

 

[Comodave]

In the photos it looks like he did not feather the original hole completely. It looks like the original hole is still about a quarter of an inch thick at the edge. It should have been feathered completely because the outside only repair is not as thick as the hull. I would feather the inside so that the outside patch and the inside patch would come together and bond to each other. You can repair it from the outside only but it would need to be feathered completely so the repair ends up as thick as the original hull.

 

[DHeckrotte]

Even a 1 1/2" dia throughhull requires a pretty small hole. We're not talking about much stress here, or concentrating load at a weak spot. When I closed a couple holes in the 1/2" thick solid layup hull in our sailboat, I ground the bore clean, ground a dish in the outside, laid up multiple thicknesses of 'glass in epoxy resin (perhaps 3/16"), filled the remainder of the bore on the inside with reinforced epoxy. The epoxy resin is already a barrier coat material so no further work to the exterior was required.

There's got to be some size at which closing a hole in a hull requires restoring or continuing the structure is appropriate. Factors would include material, load, size, location. One would, for example, be much more inclined to restore the hull were one to remove a bow thruster with its 6" dia holes near the bow.

Interesting subject! I plan to have the unused throughhulls removed when the electronics are updated. I've got at least three dead transducers and I worry more about the plastic or whatever material they're made of than I would about patches done at least as well as I did above.