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Catalina/Capri 25/250 Sailor's Forums

General Sailing Forum

Fiberglass cutting

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zeil
Master Marine Consultant

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Canada
1310 Posts

Initially Posted - 10/31/2021 : 14:59:27

In order to store galley pots and pans on the shelf below the stove we would like to create an access opening in approximately the marked up location

I will make a template for the exact location of the opening

My questions

1) How would you prevent rough/splintered edges, markings and scratching the adjacent surface
2) What tools would you use for cutting the opening
3) How can one best prevent dust from flying about
4) Tools to clean-up the finished edge

Henk & Johanna
"Floating", a few off your "barnacles".
"Someday Lady" '95 C250WB #151 ('03 - 2016)
"Sea ya" 30ft Bayliner (04-2018 - 09-2018)
"Mariah" '96 C250WB #191 (05-2019 - 15-05-2023)
"Lady J" '00 C250WK #499 (05-2021 - 09-2022)

Edited by - zeil on 11/01/2021 11:16:06

glivs
Admiral

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USA
836 Posts

Response Posted - 11/01/2021 : 04:50:02

Henk, No photo with your post so not sure of your workspace but if room allows I would tape (painter�s tape) the perimeter outline to be cut, mark your lines clearly on the tape and use an oscillating tool with a half-circular cutting blade for the straight edges. Radius the corners by drilling them out. As for dust, have your first mate hold a shop vac nearby. You will have dust but a rotary tool would create far more. Not sure how you want to finish the edges or if you are considering any type of trim, but a sanding block would be a first step to cleaning the edges. Not very innovative but well tested. How are you planning to finish or cover the edges?

Gerry Livingston, Malletts Bay, VT
"Great Escape" 1989 C-25 SR/WK #5972

zeil
Master Marine Consultant

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Canada
1310 Posts

Response Posted - 11/01/2021 : 10:21:09

Thanks Gerry... I hope an image is now included. I'm still struggling to post photos ever since something went amiss between our forum and Shutterfly.

It's reassuring to have your note and tool suggestion before starting this scary business of cutting into exposed fiberglass surfaces.

At this point I intend to leave the cut edges sanded smooth while planning to cover the opening with a white melamine, teak edged, Velcro'd cover.

The new opening provides increased storage usability and access to store galley utensils and cooking pots and pans

Voyager
Master Marine Consultant

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USA
5320 Posts

Response Posted - 11/01/2021 : 18:37:37

Hi Henk, when I first read your question I thought about a vibrating tool (Finetool) with a carbide blade or a Sabresaw with a metal-cutting blade (fine teeth). I�d use a plug-in tool rather than a battery-based tool to get higher speed and faster cutting. The benefit of a sabresaw would be that you can cut a smaller radius. You can also drill holes at the four corners to make a tighter radius.
I second using painters tape to minimize tear-out or splintering on the edges. And use a shop-vac to keep the dust down.
I�m not sure how you�d finish the edge - would you square them off or round them over?
I see you�d frame the opening with teak and melamine, so it�s a minor point.

Bruce Ross
Passage ~ SR-FK ~ C25 #5032

Port Captain � Milford, CT

Voyager
Master Marine Consultant

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USA
5320 Posts

Response Posted - 11/01/2021 : 18:45:04

Here�s another carbide tool you can put into a router-type tool or rotary cutter.
See: https://www.toolstoday.com/v-13915-46264-k.html

Like any router, it�s best to build a jig to allow you to follow a straight edge or a pattern.

Bruce Ross
Passage ~ SR-FK ~ C25 #5032

Port Captain � Milford, CT

glivs
Admiral

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USA
836 Posts

Response Posted - 11/02/2021 : 05:11:12

Henk, you have enough experience to know what tools you are comfortable with but I agree with Bruce that a Sabresaw with a fine blade might be easier to manage because you are positioned directly "above" your cutting line and thus easier to maintain a near perpendicular edge. It is scary to cut into your boat; just think it through and go carefully.

Gerry Livingston, Malletts Bay, VT
"Great Escape" 1989 C-25 SR/WK #5972

Voyager
Master Marine Consultant

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USA
5320 Posts

Response Posted - 11/02/2021 : 21:40:09

Henk, rather than make your first cuts right on the line you�ve drawn on the cabinet, try a test cut inside the rectangle just in case the saw gets out of control. You can always make adjustments then try again until you get it worked out right. Once you can control the blade accurately, only then try your final cuts. Again, I would be inclined to make a jig or a wooden guide for my saw to follow rather than doing it freehand. Never know when you might get a wicked case of hiccups!

Bruce Ross
Passage ~ SR-FK ~ C25 #5032

Port Captain � Milford, CT

Voyager
Master Marine Consultant

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USA
5320 Posts

Response Posted - 11/03/2021 : 06:10:23

Bruce Ross
Passage ~ SR-FK ~ C25 #5032

Port Captain � Milford, CT

zeil
Master Marine Consultant

Members Avatar

Canada
1310 Posts

Response Posted - 11/03/2021 : 10:17:29

Thank you guys for providing alternatives for tackling "finished surface fiberglass cutting".

To make sure, I'm planning to obtain an exact location template of the opening from the other boat. (the approx hand drawn location lines shown in the photo are only on the photo)

It'll be my pleasure to document and provide photos.

OLarryR
Master Marine Consultant

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USA
3411 Posts

Response Posted - 11/03/2021 : 15:33:23

It takes some patience but you can make a fairly clean cut using a Dremel tool and one of their thin diamond wheel cutters. That�s how I cut a rectangle to install a new switch panel in front of the sink (photos on my website). I forget how thick the fiberglass was but believe it was around 1/8�. The Dremel cuts well for thin thicknesses using speed versus torque but as thickness increases, then it may bog down.

Larry
'89 Robin's Nest#5820, Potomac River/Quantico, Va
http://catalina25.homestead.com/olarryr.html

dmpilc
Master Marine Consultant

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USA
4593 Posts

Response Posted - 11/04/2021 : 05:25:16

If you desire rounded (radiused?) corners, perhaps cutting those with a small hole saw before doing the long straight cuts.

DavidP
1975 C-22 SK #5459 "Shadowfax" Fleet 52
PO of 1984 C-25 SK/TR #4142 "Recess"
Percy Priest Yacht Club, Hamilton Creek Marina, Nashville, TN

bigelowp
Master Marine Consultant

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USA
1757 Posts

Response Posted - 11/04/2021 : 06:44:28

First drill a hole that the saw blade will fit in. If you are seeking rounded corners you could drill four holes to achieve the contour. Then as people have stated use the highest speed/finest tooth saw for the smoothest finish. I would consider looking at CD for a drawer or door that might look similar to what you have already for cosmetics. If not, you can get material, similar to auto door edging to make the opening smooth tot he touch.

Peter Bigelow
C-25 TR/FK #2092 Limerick
Rowayton, Ct
Port Captain: Rowayton/Norwalk/Darien CT

GaryB
Master Marine Consultant

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USA
4299 Posts

Response Posted - 11/07/2021 : 23:45:34

I�d recommend rounding off the corners if possible. Square corners can create a stress point that may lead to cracking later on. A hole from a 1/8� to 1/4� drill bit should suffice to round the corners and reduce the chances of cracks forming.

Association Member

GaryB
Andiamo
'89 SR/WK #5862
Kemah,TX

zeil
Master Marine Consultant

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Canada
1310 Posts

Response Posted - 11/09/2021 : 18:47:08

Following much appreciated advice I took the plunge and cut the service opening below the stove.

From our other Catalina we made a cardboard template and copied the exact location and size of the opening to this boat

Using masking tape we then copied the outline on the tape-off area. Before drilling and cutting we used a plastic shopping bag and taped this to the inside of the galley counter to eliminate as much dust as possible

Next we drilled 1/4" holes in all 4 corners. With the oscillating tool using the half round cutting blade we cut through the 1/4" - 3/16" fiberglass. Using a wood type file and sandpaper the corners and edges were rounded and smoothed. I'm very happy with the result and happy with super easy access to an existing storage area.

glivs
Admiral

Members Avatar

USA
836 Posts

Response Posted - 11/10/2021 : 16:33:44

Looks great Henk....keep us posted as you continue.

Gerry Livingston, Malletts Bay, VT
"Great Escape" 1989 C-25 SR/WK #5972

zeil
Master Marine Consultant

Members Avatar

Canada
1310 Posts

Response Posted - 11/14/2021 : 17:25:36

Cutting into exposed, interior fiberglass is scary business. Make sure it is in the right place and do it only once. Preparing and taping the "to be cut edges", forestalled any splintering which were then filed and sanded smooth.

Thank you guys for all your help!!

A new Velcro "teak-lined melamine cover", nicely hides the service access opening

This is the template used, It was copied from our '96 C250 WB who is equipped with the galley settee side access port.

Edited by - zeil on 11/15/2021 12:38:00

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