Custom 54" cat twin

[DISAR]

the mold is polished, especially the deck. The "mat" finish comes out because of the PVA, although I have seen another one which says it gives a shiny finish and I will try it if I make another one. But in any way I will not take the risk and use wax.

It is difficult to use a buffer on the bottom part on the small areas of the sponsons. I need a small buffer with small radius, do you know any?

[martno1fan]

Yea PVA gives a dull finish but i supose you could allways buff up the part once its made,probably easier that way.Id just use wax no pva on the mould,once you have done it this way you wont go back to the pva,the finish is so much better.Just be sure to give the mould plenty of wax lol.Great way to help when removing the parts is compressed air.The first time i omited the pva i was scared it wouldnt release easy but once the moulds been used it becomes easier with every part.Your moulds broken in so it should be fine ,why not try it on the lid and the deck first and see the diference.

[DISAR]

excellent, you know these things very well...I tried to polish the boat before I paint it but no much success but I think that the polishing cream that I have is very fine. Two days ago I found a medium one which I tested and seemed to work, I will try that as well in the future.

In the past I was using wax, 9-10 passes and luckily enough I had success in every attempt. I made 3 complete molds, and 3 boats all came out fine, no detachments nothing...
About 3 months ago I followed the same way in a hatch and disaster half of the gel coat sticked to the mold. Very difficlut to repair the mold but I think I am close enough. Since then I started using pva on everything because it is 100% guaranteed and the products come out so easy.
I tested the wax that you told me in the sprintcat hatch, 10-12 coats I think and I must admit that it is really good but again I had a some gel coat detachment on one edge. I don't undertand why
-I use gloves
-No moisture
-I buff the wax with clean cotton cloth
-I leave minimum 1 hour betwen coats

By the way, what do you think shall I do the repair the mold? I grinded off the edge about 1mm deep and 3cm long. Polyester Putty and sanding-polishing?

[martno1fan]

Hi mate,without seeing the damage or where it is its hard to say why it happened.One thing i will say is for moulds try and use tooling gel as its harder than normal gelcoat.
For repairs i make my own putty using gelcoat and either milled fibres or just some talk depending how large the damage is(small cracks scratches etc i use talc).if you get some clear plastic off packaging(kids toy boxes) you can tape this over small damaged areas after filling with the mixture and smooth it over gently this will allow the gel to cure faster and leaves it smooth and very little sanding after.As you know gelcoat doesnt like the open air and sometimes wont go off propperly on its own so rather than add things to it i cover it with clear tape or as above to keep the air out.
Gelcoats a tricky substance and air temperature moisture etc causes all kinds of funny things to happen lol.
Mart
3m marine compound is the best ive found,try it.Comes in diferent grades,id go for a medium and a fine or finishing .

[DISAR]

Thks for the advise, Pls see the photo below where the damages are, there are two

[martno1fan]

Looks like its been caused by an air void between the laminate and gelcoat ? do you use any chopped strand matt ? id use a layer of this before using any cloth in fact on moulds i use only mat.First i mix some bog using chopped strands and resin,my moulds are all polyester i dont use epoxies ,i know many like it but i hate it and its hazourdous to health and ive never found it any stronger than poly resins in our boats in fact contrary to many claims i was given a carbon kevlar hull that hit a polyester csm boat and the kevlar boat split right along the deck whereas the poly hull was un damaged so which one was stronger ? also the kevlar one cost 3 times as much lol.
Mart

[DISAR]

Thanks Mart, yeah maybe there was air in there...(I must check my eyesight hahaha) as a first one I use a thin mat (we call it spider) or a thin 50-60gr rovin but this is very tricky and use it only on easy surfaces

[martno1fan]

Get yourself some chopped strands about 1/2" long mix this with some of your resin and spread this into all awkward corners then lay your chosen material and resin as normal.This bog mix will eliminate any air voids,i use this mix in all my strakes on the boats also this makes for strong hulls as all the strakes are solid glass which keeps them nice and stiff.I use a silicone icing spreader to work it into position they work great and clean easy as any resin will just come off when set as it wont stick to silicone .Hope this helps .
Mart

[DISAR]

Thanks, Mart. This is a big boat there!
I used polyester putty-filler on the steps and some nasty corners and then started laminating. I will try your way as well.

[minigazz]

Hi there, I am thinking of building an rc boat in a similar way to yours and I was wondering how you would go about joining the two sections?

[DISAR]

Good sanding with 80grit both surfaces near the seam

1)Align top and bottom
2) I use masking tape to keep in place
3) Masking tape to cover all the seam from the outside
4) 24 hr epoxy mixed with microbaloons and with some color same as the gel coat on the seam from inside
5) Before that cures, I lay two stripes of glass cloth 160gr and kevlar tape with 24hr epoxy

[martno1fan]

Thanks, Mart. This is a big boat there!
I used polyester putty-filler on the steps and some nasty corners and then started laminating. I will try your way as well.

Problem is with putty it will tend to crack and chip away,the bog mix i use has the small fibres of glass in so this makes it very strong and it will never crack or chip.it also makes laying your clotth in the mould easier as you dont need to worry about it forming into the tight curves and sharp edges of the steps or strakes etc.
Mart

[DISAR]

finished painting and decals, shortened wires and next run will be with with 1527s 1y 6s

[DISAR]

one more

[millzee]

one more

that is beautiful!! Great build, looks sleek, fast and stylish,
I think you've just insired my 3rd build, a couple of 1717's in something like that, 45-50"