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Re: Sand Blasting

Patrick McAneny
 

Joel, Bill pointed that out to me ,but what he sent and I read ,left me wondering if they were referring to using high pressure above the waterline,which they stayed several inches below. In any event ,as they did not blast it to the point that they even removed all the paint ,I cannot see how any water could of penetrated the gel coat ,certainly does not appear to be the case and once the sanding was done the hull was smooth as can be and appeared completely dry. I suppose if the operator was not careful ,damage could be done ,perhaps that is why they stopped short of removing all the paint. The work is being done at Haven Harbor in Rock Hall and they have a very good reputation for doing excellent work. I will probably  not apply the barrier coat until spring ,with Covid ,I think we will probably sit this winter out .
Thanks,
Pat


-----Original Message-----
From: amelforme <jfpottercys@...>
To: main@AmelYachtOwners.groups.io
Sent: Tue, Aug 18, 2020 8:15 am
Subject: Re: [AmelYachtOwners] Sand Blasting

Hi Pat. Before you paint the bottom or apply any coatings, be certain to have the bottom checked with a moisture meter over its entire surface. It states in the Amel owner’s manual in the third section of the users guide several things about using high pressure washing below the waterline. It says to never use more than 1130 psi/80 bars of pressure, always from a distance of more than 8 inches/20cm, and at an angle of 45 degrees and never perpendicular. It is generally recognized that using pressure above 2500 psi is detrimental to any polyester or epoxy resin fiberglass laminate.
 
Be sure that you have an acceptable level of moisture in the laminates before you proceed to refinishing.
 
I have seen first hand the detrimental effects that extreme high pressure washing can produce and it is never pretty. If you would find it helpful, give me a call after you get your moisture readings and I’ll give you some advice based on experience that should be helpful.
 
All the best,
Joel
 
           JOEL F. POTTER ~ CRUISING YACHT SPECIALIST, L.L.C.
                                         The Experienced AMEL Guy
UNSURPASSED AMEL MARKETING EXPERIENCE AND PRODUCT KNOWLEDGE
                                  Office 954-462-5869  Cell 954-812-2485
 
From: main@AmelYachtOwners.groups.io <main@AmelYachtOwners.groups.io> On Behalf Of Patrick McAneny via groups.io
Sent: Tuesday, August 18, 2020 7:54 AM
To: main@AmelYachtOwners.groups.io
Subject: Re: [AmelYachtOwners] Sand Blasting
 
James, There was one area ,about 8 sq. inches where there must have been a void where the first or last layer of fiberglass was partially removed ,the manager said that sand blasting would have opened it up as well. It will be a simple fix and I will be doing about three or four coats of barrier coat . There is no other area where all the paint was removed ,so no damage to the gel coat,after a light sanding the gel coat is as smooth as can be. The yard did not consult with me on power washing as opposed to sandblasting ,which concerned me ,but I am glad they went with it. 
Thanks,
Pat
 
-----Original Message-----
From: James Alton via groups.io <lokiyawl2@...>
To: main@AmelYachtOwners.groups.io
Sent: Mon, Aug 17, 2020 7:56 pm
Subject: Re: [AmelYachtOwners] Sand Blasting
Pat,
 
   This sounds like an interesting option to me and apparently there was no damage done to your gel coat.   I like the fact that you avoided using harsh chemicals.  You also checked your boats bottom for loose putty and voids in this process whether you realize it, since 5000 PSI can take anything off that is not well attached and can open up voids near the surface!  I had the bottom of my boat checked with an ultrasound during the initial surgery looking for voids, delaminations etc. and non were found.  That would not be the case on many non Amel hulls.  It seems that Amel does a very good job with their laminations in getting out all of the air, especially at the critical gel coat interface.  Really glad that this worked out for you.
 
James
SV Sueño
Maramu #220
 
On Aug 17, 2020, at 5:02 PM, Patrick McAneny via groups.io <sailw32@...> wrote:
 
A few weeks ago I mentioned that I intended to have by boat sandblasted , I paid for it ,but they did something different,maybe better. I went to see what progress had been made on repairs . The bottom paint ,several layers was mostly gone ,with maybe a half thin coat still attached to the hull. I was confused ,since I expected it to be blasted down to the gel coat . What they did was to use a 5000 psi powerwasher with a rotating turbo head which blasted most of the paint off . I missed that part ,but while I was there a workman used a 7" orbital sander with 60 grit to take it the rest of the way down to the gel coat. He did a 20 sq. ft. area in about 15 minutes . So it should take about 9 hrs of sanding. What he did looks perfect and no concerns for damage to the gel coat. 
Just thought I would put this out there, as another option to sand or soda blasting
Pat
SM Shenanigans 
 
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