Choices

New here but have spent some time searching the posts. I am on the verge of getting Bruce Roberts Coastworker 28 plans with a view to building in GRP.
This isn't my final choice yet but it will be something like.
I have read good/bad about allsorts. So my choices are (I think)

Female or Male mould - I reckon the biggest problem with a male mould is fairing and painting etc and then turning the hull over (pushed for space). I like the idea of a female mould but read all sorts about what to line it with.
Foam or Balsa - I understand the good and bad about them but also understand that you should never try to poly on epoxy but doesn't a lot of balsa come pre epoxied on the end grains.
I can't get my head round vacuum bagging. If you bag the area then create a vacuum, surely the whole thing would implode therefore dragging the core off the outer skin??
Also - I have considered the following-
Using 6 mm marine ply over stringers/frames/bulkheads (well epoxied)
Glass it to a good thickness outside
Balsa/foam the inside above the waterline including both sides of the bulkheads and the stringers
Glass the inside.
In effect I reckon this would give me a permanent mould that would stay as part of the boat. Little waste and a hybrid grp/core/wood epoxy.
Thoughts???

Arthor

 

me again. I know the last option leaves me with fairing and painting the hull but I reckon that if I have a tipping cradle, I can do it with the hull upright
Mad but possibly groundbreaking

 

I know you want to build from scratch, been there done that. (3 times) and not much I say wiill deter that "I gtta do it" feeling, but think real hard about renovating. The older boats in your size range are pretty easy to find cheaply. If you want you can easily strip a boat down to bare fiberglass and then rebuild it the way you want, but you will save many hours of labour, and keep an old boat floating

 

How about strip planking with foam?

Setup your stations, attach foam strips to them, and glue them together, fair this structure, then laminate over it. Fair again, and finish the bottom, and leave the area above waterline undone. (turning the hull will damage your paintjob inevitably, make sure you have faired the hull completely)

Then turn over the hull, remove the stations, and laminate the inside. (could be infused)

Most balsa comes unprimed. Primed balsa is done with polyester resin.

 

many thanks for the input guys

arthor

 

Author,
If you do purchase Bruce Roberts plans they come with detailed descriptions on building the strong back (male mold) how to fare the mold and then how to cover with foam or balsa. I built a 78' Bruce Roberts (I had a navel arch. resize his plans) and found them very complete, and the book he ships with the plans is also good., I still use it.

Good luck, (but really consider rebuilding)

 

Thanks again

I have also been considering the following.

Tolman Jumbo Skiff
Glacier Boats - Great Alaskan
Bateau DE 23/26 or Carolina Sport Fish.

I am happy that I can do the stitch and glue thing but I am also considering a bare hull in GRP that I can finish. Sort of best of both really.
I have been looking at the Wilson Flyer 24'. I know they don't look great but I am developing a soft spot for them. I would be doing estuary and coastal work along with river and broad canals.
What are your thoughts on the Wilson Flyer. I have heard conflicting things about them. Stability etc.

thanks

 

The boats listed above will be MUCH heavier if you build them in GRP, and they will therefore require bigger engines and suck up more fuel. Just be sure you take into consideration the fact that GRP boats are very heavy compared with plywood, and one-off they cost more in money and time, too.

 

ply and foam

thanks again guys.

I have been looking at foam as well and I reckon that ply and foam can be used together.

1)Set up thetransom, stringer and bulkheads as a mold with trapezoids on the edges of the bulkheads.
2) 2 layers of 3/8 ply for the bottom epoxied together and epoxied and screwed into the stringers, bulkheads and transom.
3) 1/4 inch ply for the sides epoxied and screwed to the bulkheads (through the trapezoids)
4) foam the outside of the sides in 1/2 inch foam epoxied and screwed to the 1/4 inch ply.
5) glass all of the outside. Flip her over, foam the insides with 1/2 inch foam.
6) glass the inside.

What I reckon I am doing here is using a thin plywood mold for the sides that I leave in place as a rigid (ish) core. Does this idea have any merit and what would my fasteners have to be made of if I want to leave them in?

thanks again.