Does anyone have any experience making a mold? i would like to make a layout boat mold out of some blue dock foam i picked up off the side of the road. Not for production purposes but as a hunt club project. My question is, could i fair the blue dock foam to the shape i wanted it, shrink wrap it, and lay fiberglass over top of the shrink wrap? will the fiberglass eat the plastic? Once i popped this off of the plug i would fiberglass ash as support on the inside. WOULD THIS WORK? thanks guys!
making a boat mold questions
- Thread starter sean kane
- Start date
Scott Bell
Active member
Sean,
That idea will work (making a plug from foam and building the boat around it). You can do a small test to see if the glass will eat or stick to whatever plastic you are trying to use (and also if it will stick to it or not).
When I made my mold, we glassed over the plug then waxed it really well using mold release wax and coated it with pva mold release spray (essentially a spray-on plastic). That combination worked out really well. If you are wanting to make more than one final boat, you'll probably want to go that route.
Also, avoid inverted angles!
\___/ is good...the new part can slide down off of the plug.
/.....\
\___/ is bad...you will need to do this in 2 parts and then glass the top and bottom together. I even avoided perfectly vertical sections except for a 1" area for overlapping the top and bottom halves of my boats (and in the transom area). Again, that's if you don't want to destroy your plug when trying to get it out of the boat.
That idea will work (making a plug from foam and building the boat around it). You can do a small test to see if the glass will eat or stick to whatever plastic you are trying to use (and also if it will stick to it or not).
When I made my mold, we glassed over the plug then waxed it really well using mold release wax and coated it with pva mold release spray (essentially a spray-on plastic). That combination worked out really well. If you are wanting to make more than one final boat, you'll probably want to go that route.
Also, avoid inverted angles!
\___/ is good...the new part can slide down off of the plug.
/.....\
\___/ is bad...you will need to do this in 2 parts and then glass the top and bottom together. I even avoided perfectly vertical sections except for a 1" area for overlapping the top and bottom halves of my boats (and in the transom area). Again, that's if you don't want to destroy your plug when trying to get it out of the boat.
Last edited:
Steve Sanford
Well-known member
Sean~
Scott's info re mould release wax and PVA are what I used last time I built a one-off. Other options are wax paper (taped on with Scotch tape) or cellophane. I would be leary of shrink-wrap only because I tried using polyethylene (typical vapor barrier, drop cloth sheet plastic) once. Although it will not stick to the 'glass (I'm assuming you'll be using polyester resin), it wrinkled alot when we started wetting out the first coat of mat - the wrinkles would have transferred to the cured 'glass.
A couple of other thoughts:
1) Minimum layup schedule is mat-woven roving-mat-mat. This is typical for most canoe and Sunfish, etc. I'd defer to others who have built more layout boats whether you need to go heavier (i.e., another layer of roving), perhaps heavier on the bottom half (the hull) and lighter on the upper half (the decks). As you probably know, roving always need to be sandwiched between layers of mat.
2) Be sure to use the un-waxed laminating resin for the layup - and then a coat of the waxed resin to finish the cure and allow for sanding.
3) You can use wood for stiffening the hull (as in stringers) but they can rot over time. Better off to use something like a dense urethane (NOT styrofoam) foam insulation board "milled" on table saw to a triangular or trapezoidal cross section. They are 'glassed in with on a layer of mat (slightly wider than the stringer) then covered with a sandwich of mat-roving-mat (about an inch wider than the stringer). Their strength comes from the corrugated effect.
4) To fair off your foam "male mould", you can use lightweight joint compound. Then wax or cover it as above.
5) When you are actually 'glassing the layup, it really makes a big difference to have a helper. They can catalyze the resin only as you need it and you can concentrate on saturating the laminations.
Hope this helps!
SJS
Scott's info re mould release wax and PVA are what I used last time I built a one-off. Other options are wax paper (taped on with Scotch tape) or cellophane. I would be leary of shrink-wrap only because I tried using polyethylene (typical vapor barrier, drop cloth sheet plastic) once. Although it will not stick to the 'glass (I'm assuming you'll be using polyester resin), it wrinkled alot when we started wetting out the first coat of mat - the wrinkles would have transferred to the cured 'glass.
A couple of other thoughts:
1) Minimum layup schedule is mat-woven roving-mat-mat. This is typical for most canoe and Sunfish, etc. I'd defer to others who have built more layout boats whether you need to go heavier (i.e., another layer of roving), perhaps heavier on the bottom half (the hull) and lighter on the upper half (the decks). As you probably know, roving always need to be sandwiched between layers of mat.
2) Be sure to use the un-waxed laminating resin for the layup - and then a coat of the waxed resin to finish the cure and allow for sanding.
3) You can use wood for stiffening the hull (as in stringers) but they can rot over time. Better off to use something like a dense urethane (NOT styrofoam) foam insulation board "milled" on table saw to a triangular or trapezoidal cross section. They are 'glassed in with on a layer of mat (slightly wider than the stringer) then covered with a sandwich of mat-roving-mat (about an inch wider than the stringer). Their strength comes from the corrugated effect.
4) To fair off your foam "male mould", you can use lightweight joint compound. Then wax or cover it as above.
5) When you are actually 'glassing the layup, it really makes a big difference to have a helper. They can catalyze the resin only as you need it and you can concentrate on saturating the laminations.
Hope this helps!
SJS
Eric Dellamater
Well-known member
would agree with just about everything Steve said...one thought though is how long do you expect to use this boat and how will it be stored in the off season? Reason I ask it the use of wood for strength. It is a given that eventually the glass will crack and allow water or water vapor into and around the wood, which will then not be able to dry out, and thus rot...however, if used lightly, stored indoors this should last for years and years. I have a skiff that I made, has wooden dowels buried into the keel (under about 4-5 layers of glass) this is 10+ years old, stored outside by the shed, no issues yet.
you can get crazy expensive, or just slap it togther, depends on you and your tastes.
I agree with everything else mentioned. PVA is a God send.
5200 on the seam and a few pop rivits to hold it together while the 5200 is curing, you are golden.
you can get crazy expensive, or just slap it togther, depends on you and your tastes.
I agree with everything else mentioned. PVA is a God send.
5200 on the seam and a few pop rivits to hold it together while the 5200 is curing, you are golden.
Lou Tisch
Well-known member
Sean,
If you are figuring on designing the boat so the deck overlaps the hull...5200 & rivets can work nicely. We used that on our Brant II.
If you have a flange for the deck and hull that mate together (flat/flat)...I would recommend grinding the mating surfaces, wetting out and rolling 3 oz. CSM (Chopped Strand Mat) onto that surface and then clamp. We use metal plates with clamps to hold until cured (overnight). We've never had any delamination problems with this layup/assembly.
This is a picture of our Whistler, clamped up waiting for overnight cure.
Lou
View attachment Whis-M-L-07.jpg
Deck with everything ground and prepped for assembly. Note the flange around the perimeter. Prepped with 24-36 grit paper.
Everything else has also been sanded so there are NO fiberglass needles or edges to catch a finger or boot on.
View attachment Whis-M-L-08.jpg
Boat upside down, hull laid on top to check fit.
View attachment Whis-M-L-09.jpg
Hull/deck laminated together with 3 oz. CSM with plates and clamps. Once the clamps are pulled, the bulkheads will be glassed in along with the short ribs.
View attachment Whis-M-L-10.jpg
Whistler finished, sitting on crate bottom during prep for shipping.
If you are figuring on designing the boat so the deck overlaps the hull...5200 & rivets can work nicely. We used that on our Brant II.
If you have a flange for the deck and hull that mate together (flat/flat)...I would recommend grinding the mating surfaces, wetting out and rolling 3 oz. CSM (Chopped Strand Mat) onto that surface and then clamp. We use metal plates with clamps to hold until cured (overnight). We've never had any delamination problems with this layup/assembly.
This is a picture of our Whistler, clamped up waiting for overnight cure.
Lou
View attachment Whis-M-L-07.jpg
Deck with everything ground and prepped for assembly. Note the flange around the perimeter. Prepped with 24-36 grit paper.
Everything else has also been sanded so there are NO fiberglass needles or edges to catch a finger or boot on.
View attachment Whis-M-L-08.jpg
Boat upside down, hull laid on top to check fit.
View attachment Whis-M-L-09.jpg
Hull/deck laminated together with 3 oz. CSM with plates and clamps. Once the clamps are pulled, the bulkheads will be glassed in along with the short ribs.
View attachment Whis-M-L-10.jpg
Whistler finished, sitting on crate bottom during prep for shipping.
Last edited:
Lou Tisch
Well-known member
Good call Carl. That was the problem.
Thanks,
Lou
View attachment Whis-M&L-07.jpg
View attachment Whis-M&L-08.jpg
View attachment Whis-M&L-09.jpg
View attachment Whis-M&L-10.jpg
View attachment Whis-M&L-10.jpg
Thanks,
Lou
View attachment Whis-M&L-07.jpg
View attachment Whis-M&L-08.jpg
View attachment Whis-M&L-09.jpg
View attachment Whis-M&L-10.jpg
View attachment Whis-M&L-10.jpg
Last edited:
Scott Farris
Well-known member
Lou,
You've given me clamp envy, I thought my scull oar lamination shot was impressive but....my butt is kicked ;^)
View attachment fixture glued side.jpg
You've given me clamp envy, I thought my scull oar lamination shot was impressive but....my butt is kicked ;^)
View attachment fixture glued side.jpg
Lou Tisch
Well-known member
Scott,
Clamp Envy...that's a new one. I like it. Ok........here's some more with clamps near the end.
Lou
Keeping in line with the thread. The orange objects are the hull & deck molds..typically 6-8 time thicker than the
actual parts to be pulled. This must be laid up in multiple layers. After the plug was made, we laid down a good layer of
isothalic gel coat. Once you can write on it with a ball point pen, we laid down our first layer of isothalic resin and CSM and
then a layer of cloth. That was allowed to cure and then we ground it and began layers of CSM, heavy cloth and a regular
laminating resin. Once done and cured, the mold can then be pulled from the plug (usually destroying the plug) and then
the gel repaired as needed and buffed, ready for laminating.
View attachment AA-B2X-001A.JPG.JPG
Brant II-X Molds on racks and parts on the other rack
View attachment AA-B2X-001B.JPG.jpg
Hull mold with gel coat applied. About 20 mil thickness.
View attachment AA-B2X-002.JPG.jpg
All our glass is on a rack, rolled out and cut to specs so there are no surprises or shortages during lamination.
View attachment AA-B2X-003.JPG.jpg
All the glass, laid out and ready for laminating
View attachment AA-B2X-004.JPG.jpg
This is our wet-out table. We can wet out the heavier CSM and the Knytex 1708 which makes it easier and faster to laminate.
The table is covered with cardboard (refrig boxes) and you can see that it's been used multiple times.
Clamp Envy...that's a new one. I like it. Ok........here's some more with clamps near the end.
Lou
Keeping in line with the thread. The orange objects are the hull & deck molds..typically 6-8 time thicker than the
actual parts to be pulled. This must be laid up in multiple layers. After the plug was made, we laid down a good layer of
isothalic gel coat. Once you can write on it with a ball point pen, we laid down our first layer of isothalic resin and CSM and
then a layer of cloth. That was allowed to cure and then we ground it and began layers of CSM, heavy cloth and a regular
laminating resin. Once done and cured, the mold can then be pulled from the plug (usually destroying the plug) and then
the gel repaired as needed and buffed, ready for laminating.
View attachment AA-B2X-001A.JPG.JPG
Brant II-X Molds on racks and parts on the other rack
View attachment AA-B2X-001B.JPG.jpg
Hull mold with gel coat applied. About 20 mil thickness.
View attachment AA-B2X-002.JPG.jpg
All our glass is on a rack, rolled out and cut to specs so there are no surprises or shortages during lamination.
View attachment AA-B2X-003.JPG.jpg
All the glass, laid out and ready for laminating
View attachment AA-B2X-004.JPG.jpg
This is our wet-out table. We can wet out the heavier CSM and the Knytex 1708 which makes it easier and faster to laminate.
The table is covered with cardboard (refrig boxes) and you can see that it's been used multiple times.
Lou Tisch
Well-known member
View attachment AA-B2X-005.JPG.jpg
Above is the hull laminated and awaiting cure. We layup with a 2 oz layer of CSM, followed by a layer of Knytex 1708 that is pre-wetted and squeegeed to
remove excess resin and assure of full contact of 1708 with the CSM.
The keel area is overlapped by about a foot on each side of the keel....down one side, into the keel and up the other side and continued about a foot,
View attachment AA-B2X-006.JPG.jpg
The deck is typically laminate with overlapping layers of 3 oz. CSM, reinforced with 1708 in critical areas. Transom is clamped into place and laminated over.
View attachment AA-B2X-007.JPG.jpg
Deck & Hull pulled from the molds and laid out for work.
View attachment AA-B2X-008.JPG.jpg
Scott......here's another of my favorite.....clamp pictures. Reminds me of a millipede.
View attachment AA-B2X-009.JPG.jpg
Jumping ahead to the boat fully assembled.
Last edited: