Hard Dodgers

[Steve M]

Hi all,
 I received an indicator that my blog site was being discussed by this group.  So I thought I might chime in and offer some help with any questions you have.
I noted in some of your discussions that there was conjecture as to what materials I was actually using, well to answer this, most of the Dodgers that I have built, and that you see in the pictures were built in female molds, that were constructed on top of the individual boats.
The mold was then removed to a suitable place and a fiberglass and cored dodger was constructed inside it.
The female molds I produced were one-shot affairs only, possibly a second dodger could have been pulled from them but that was not the intention.
These female molds were built from very cheap interior type of shiny surface plywood or masonite, with the shiny side facing in.  They were assembled on the boat, after much cutting and hacking and trimming and guessing and re-cutting.
The adjoining edges were basically, and roughly glassed together with fast epoxy every two or 3 inches, then a rough wooden framework was glassed over this to lock in the general shape.
When the female mold was removed to the workshop the interior joins were bogged and filleted, sanded smooth and sealed.
Window inserts were placed into the mold, which would create rebates for the Windows.
This process produced a reasonably good dodger and as light or as heavy as you care to make it dependent on the core material and the lamentations used.
There was however one really bad downside to this method and that was the effect the weather played on the mould.
  Invariably, changes in humidity and temperature while building a mould would cause the material used to distort and buckle and although these distortions were not really great they were not acceptable for a finished job.  If you copped a bit of rain halfway through you could darn near chuck the whole thing away.
This fact alone, was what stopped me producing these dodges in Washington (Seattle).  A place where they were really desirable to have.
Since those early days I have spent lots of time in manipulating flat panels be they composite or plywood and coupled with my learning to use CAD some years back it has totally turned the whole dodger thing around for me.
Where as before, I had to do drawing after drawing by hand, and then had to do a mock up on the boat and still hope that it was right, now, once I have a few basic measurements and have established the right parameters I can draw up a complete dodger and cut it and slice it in any direction I like which allows me to create a jig surface.
  Coupled with this of course is the ability to do panel unrolled.

This feature in itself within CAD (or it leased the one I use) is really fantastic and simplifies the designing job immensely.
If the designer has a good knowledge of the way materials behave, and works within the boundaries of the materials, then the item can be a complete success and without great difficulty to build.
Rather than ramble on, I'd be happy to answer any questions (if I can) that you may have.
I posted some more pictures on my blog and will try and post some more of a female mold being constructed

Steve Marshall

[ebb]

Thanks for the visit Steve.
Amazing you are on the other side of the globe and can give us your neighborly input and experience. That's just great!  You whippersnappers have the great benefit of CAD.  Envy that ability.

 Tony and I - and Commander Pete for sanity sake - having an active discussion on the subject IS what this Pearson Ariel/Commander Association tech forum is ALL about.
From the 'hit' count we gabbers are obviously getting listened to by other boat owners who probably want a dodger - whether they are cruisers or weekenders.
 I  wish more A/C owners would join in, give this discussion more legitamacy.  It's a worthy subject that nobody could not have an opinion on - especially which style is more appealing.

Now we have an international contributor, a pro who is willing to share his experiences with us!

If you want a hard dodger, and you are a classic plastic  boat owner, you are probably not made out of money and have to make one yourself.
Steve Marshall 'says', take your small tools down to the boat and some panels and start messing around making some frames, some bending forms and see what you come up with in terms of the space you want. The boat will talk to you.  
If you like the idea of wrap or bent panels, you make some bending frames, tack and cross brace them to the coach roof and the bridgedeck (you can fill the holes back in later) and start forming that dream dodger.

Tony is showing how to make a 3D sketch.
Not sure how his form translates into a female mold but if Marshall says it can be done ......then make it so!

To proceed toward a female mold:
 that is when you take your think pieces  and replace them what will be the inside surface with 1/8" hard-board.
Even here you can make twin holes and stitch panel seams together with wire when bending together more than one panel edge to edge.

When you got the overall shape you want:
Before you remove anything you stabilize the top with cut to fit plywood and two-by.  You build another frame on the TOP and SIDES of your model to keep it in that shape - because the original frame the skin was built on is of no more use.  It's like bridge-work   You are ofcourse making the cradle and legs that will be under the curved form that when it's turned over you will be laminating INTO.

  [When you get a book on stitch-and-glue, you see that after tacking your shape together with epoxy goop, you snip away and pull the the wire and proceed to make beautiful fillet seams.  I would get a book on S&G just to understand the process for the dodger mold.]
 
 Fiberglass and foam in a female mold is another kettle of fish.
Using Marshall's female mold idea you'll be building up the dodger from the inside - your first layer inside is what will be seen on the finished product outside.  A boat building shop would spray in a gel coat on a well prepared surface. (I have heard of as many as 20 coats of carnuba, each polished, plus mold release spray... to prep the mold.)

A boat owner will be using the mold just once, so it is possible to be more casual.  In fact, no matter how well you prep the mold, it will probably have to be disassembled to get it off your new dodger.
It is possible to make the dodger in a female mold with epoxy.  Your first layers will be X-matt, altho I have heard of an epoxy 'gelcoat' that could possibly be rolled on the mold befor the matt went in. Haven't done it.  if you don't start with color you will have a lot more surface filling and finishing to do before painting.  
If you have some experience with poly and vinylester then that is probably the way to go with the female mold method.  Sounds like that's what Steve Marshall does with most of his.

The female mold with all its bracing and understructure will be quite huge.  The dodger itself will also be multilayered and a lot of pieces of cloth, matt and foam sheet.  I think polyester takes more experience, while epoxy is more forgiving and less lethal.
Personally, even tho it's so much more expensive, I would go with 100% solids no blush epoxy. I think it's easier for a first or second-timer to use.

If I had any time left to experiment, I am convinced that a wrap style bent panel MOLDLESS dodger out of meranti would be the easiest and most gratifying way for an amateur (don't take that negatively!) or a first timer to make.  Check out stitch-and-glue DINGHY sites and you'll see what I mean.  The kayak DIY sites are often too esoteric, but often what THEY do with the method is amazing!

Thanks for dodging in, Steve!:D

[Tony G]

Ditto that thanks from over here too.  It's always good to get the input from someone that has been there-done that.  I'm always surprised at the amount of information one can glean from this forum.

Unfortunately, for me anyways, it hasn't made the decision any easier.  Laying a core into a female mould sounds like it could be tricky.  I don't know why but past experience leads me to believe so.  Vacuum bagging into a female mould would surely be more difficult than 'over' a male mould when we're talking about a pull this size.  After all, I am amatuer hour.  A smooth outer surface is a nice starting point.  That coupled with the ease of adding 'rebates' for the windows  and other 'built-ins' makes an attractive argument for that route.

Does a 1/4" to 3/8" super light, super flexible, super cheap core material exist.  Weight is an issue, after all.  If you went thinner I suppose one could easily add a few carefully placed stingers to stiffen things up a bit.  And I do like the stainless grab bars incorporated into the design.

Gawd I wish I had the time and grey matter to invest in learning a CAD program!  While I like the 'real wrap' design I think a curve that matches the curve of the cabin top just aft of the mast is most graceful and yet sexy.  We already know the arc of the cabin top truely compliments that curve and would make a nice top for a dodger.  So far all over this rebuild I've been stealing curves and borrowing angles from other parts of our boats to incorporate into my ideas.  I really believe that it adds continuity.  Just my opinion, folks.  Shoot it full of holes.

I don't feel so bad about drawing everything 'longhand' now that I heard the real deal has done it too.  HA!  Take that computer nerds!:D

[Steve M]

Hi Ebb and Tony,
 just to expand a little more on my previous comments.
 The method I described of creating a female mold, is for me, totally in the past.
As as I've worked much more now, with flat panels and found different ways to form them, other aspects have shown themselves which can certainly speed up the job.
The method I now use, and I am describing with pictures in my book, is a mixture of post-forming glassed flat panels, and stitch and glue.
Ill briefly describe the billabong style.
This style uses a series of flat panels all of which are cut from 6 mm (1/4")
There will be an inner and outer piece, for each panel, which when laminated will give a total of 1/2".
  The outer layer being cut with a slightly larger window opening (say 30 mm) to allow for the rebate.  This total thickness of half inch ply is really negligible in weight as most of the panels are cut out for windows, and this  thickness is required to provide a rebate and for other reasons.
  Now as an example of post forming, and this is not the complete picture but just to give you an idea
The Billabong Style
Cut out all of the inner 6mm flat panels, cutting their window holes (which of course is smaller than the window itself to create a flange ) Round the edge of all the window openings on the inside face only.
Cut the outer 6 mm panels (we are assuming a light weight good-quality marine plywood is being used)
Position and glue on (with epoxy) the outer panels to the inner panels at the appropriate places.
At this stage all the panels are separate squares or rectangles, with window holes and rebates.
Now with the Master face panel Patten, drawn on the table which will sort of look like a boomerang made from a series of squares.
Cover the table in clear plastic, place the panels, outer face down, in their appropriate positions edge to edge and glue together to form that one big boomerang shape.
All of these panels must follow the Master Patten precisely.
  So you will now have the inner faces all facing up towards you, and all glued together along there are joining edges
These will all be just square on butt joints and certainly don't need to be fancy in anyway.
  They do need to seal the gap between the individual panels at best, and must not allow resin to drain through.  
Sand over this entire surface so there's not blobs and lumps of glue sticking up.
  Now, glass over this entire inner surface with 600 g bi axial (do not use less weight than this) making sure the glass goes smoothly down into the window cutouts, and nicely covers the radius edge.
Just let the glass hang on through at this window .opening but keep it in nice and neat to the each will be trimmed later on
this inner surface can now be filled and sanded smooth.  Leave a strip 30 mm around the entire top edge unsanded and unpainted.
Leave the same kind of unfinished surface around the entire bottom edge but about 60 mills wide.
I specify using epoxy when glassing or gluing  plywood as the bond is far far greater than polyester or VE
when this whole business has properly cured off, about two days in good weather, the whole thing can be carefully turned over, so now the glassed face is down.
 You will now go around the entire top edge of your plywood and glassed panel and with a planer or grinder feather away the top edge down to a thickness of about 3/8 of an inch, and down the face about 2 1/2 inches  Any  resin gobs or blobs can be removed, and the glass that came through the window hole can be trimmed off so that you should have a nice neat rebate with fibre glass running right up to the inside edge.
So now you've got a big partially fibre glassed boomerang shaped thing on your table with nice neat window cutouts.  Now this next step takes utmost care.  
You will mark out a series of lines parallel to each other and equally spaced down what appears to be the pillars of your dodger face (that is the sections that you butt joined together, between the window openings)
you will then set up your skill saw, the smallest one you have with the narrowest blade and proceed to cut down these lines to a depth of about 3/8 of an inch or less.
This Kerffing of the outer plywood face allows the glass and plywood panel to be bent smoothly on what is to become radius corners of your dodger.
The positioning in the spacing of these lines is shown in my plans but you can experiment yourself you will also need to experiment with the depth on a peice plywood that has been fiber glassed.  Note this test piece of ply must have its grain orientation identical to the way yours is on your job to deeper cut and you will get creases showing on the inside.  To shallow a cut and you'll have difficulty in bending to the point where it may suddenly break on you.  So do the tests.
My plans will show a-based pattern and a simple jig all of which are done from chipboard.  The front face panel you have just created, is then bent around with great care to conform to the mark out bases line and if all is correct it will rest up against your chipboard jig.  The grooves you have cut in the pillars can then be filled back with epoxy filler (Micro fibers and epoxy resin)
The other surface can then be fiber glassed, with 600 g DB, taking extra care to a good job on the pillars and.and don't gob resin into the window rebates.
The Cambered Top
The cambered top use's  a somewhat similar method and there are some tricks here to really create a good and simple finish.
Firstly lightness is of great importance, however this hard dodger will be stood on and possibly fallen onto so it needs to be gutsy it's possibly going to support solar panels, resist possibly the boom falling on it, and God forbid  big waves dropping onto it.
So to this end a thin section is not an option.
So options are (low cost included here ) plastic honycomb "Nida Core" "Poly Core" "Plascore" I rule out virtually all of the foam cores because of their current excessive  cost.
The plastic honeycomb should cost between $60 and $80 for a full 8x4 sheet at 5/8 thick.
If your interested I can explain in general manner this top making which is way more simple than the front.
There are many little details Iv left out so as not to confuse.
I use a word recognition program ("Dragon Naturally Seaking") if you find some strange words in the all this text.
 ps I did get some pics onto my blog last night of female molding but as I say I wouldn't push that method any more
Steve Marshall

[ebb]

Steve. that's one of the greatest process posts of all time here.
I'm a DIY fan, and try to have complete thoughts on subjects - so I'm impressed and for myself thank you for it!

The female mold process does seem to be labor intensive.
I used a similar process on a male mold for the windscreen portion of LittleGull's dodger. Foam core laminate.  Unless  experienced with a good plan and access to full inventory of materials it leads to overbuilding and overweight.  I used X-matt but should have used woven cloth.

We have a great moderately priced phenolic glued phillipine mahogany plywood available here. It is rated to British standards and is usually sold as Hydroply and Aquaply. It is a planet plywood, depending on the source is available in mm or inches.  The veneers are very thin.  The mm version of 1/4" is thinner than 1/4" but still has 5 plys.  I have seen 3 ply 1/4" meranti, but won't buy it even if it is BS1088.   Meranti is cheaper and more durable (rot resistant) than okume, a popular and lighter plywood used by kayak builders.  Meranti is a much cleaner stronger plywood than marine fir ply. And made much much better than what is produced in the States.  Using meranti will make your project look that much better.

The Billabong style dodger, and the method Steve describes would work great for Tony's cab dodger.  The method is, as I keep saying, very much like stitch-and-glue building.  In fact the same wiring of panels trick can be used.
Because the panels are so thin, strength is gained in corners with the use of  epoxy fillets and the ultimate covering of the whole structure with cloth, inside and out.  In fact, if I understand it, the whole hard dodger could be made and fitted to the coachroof before the final whole cloth layers is applied.  Or perhaps the inside could have the tie layer of cloth applied and the outside done after  carpentry and fitting.

I naturally like the other Blue wrap style.  
Because the panels are all bent into curves the structure is inherently simpler, stiffer and stronger.
Imco the windscreen light could be slabbed on (without rebate) to a single 1/4" bend.  Let's call it a racing version of a hard dodger.

The problem with the Ariel is its size.  It already has a two-bump coachroof. A hard dodger will add an unintended design change to the visual volume of the sailboat.  At this moment in time a fabric and tube pram dodger is more acceptable to the eye.  One thing I've noticed is that we see canvas as separate from the boat's lines.  It helps if the fabric is a darker color.  When we make smooth and beautyful additions to a sailboat in the form of a hard dodger, we can get into trouble with the designer's original concept.  Hard dodgers are becoming more streamlined and acceptable as a structure, like the fabric pram hood, for itself.  In other words, imco, you don't want the dodger to give the impression of a designer pilot house on a pocket cruiser.  The Ariel needs a disproportionate tall hard dodger to provide access below.

It's a real problem that I wish we had more to talk about here.


With the flatter 'cambered top' imco a rib or two could be introduced or could be added later where attachment points are known for rails and solar panels.
Honeycombs are the way to go for lightness and insulation.* If this is too tech, then endgrain balsa is still available.

Steve's double 1/4" method of side construction would make a very strong and light structure especially with mm meranti.  Polycarbonate rebated into the dodger would make for a very clean looking job.  Flatter lights on the Billabong style would allow thicker and stiffer poly.  Can consider the poly as a structural component that adds strength and stiffness.
_________________________________________________________________________________________________
Cambered top:
* Using a foam or balsa or honeycomb for the core...
do you think you can get away with 1/8" ply on the top and bottom?
It could be possible to get good rigidity in the finished laminate with 1/2" core - 1/8" skins - 10oz cloth top and bottom - glass and epoxy.  

[Tony G]

Ebb

Let's just forget we ever saw that first attempt (?) at 113's hard dodger.  You're absolutely right, the Ariel just does not lend itself well to the 'motor sailer' and pilothouse look.  To that extent we're...persuing other avenues.

Why not try to form something that has the room and curves of a soft dodger with the duability and utility of a hard dodger?  That's where I'm at now.  Date and Time stamp it, tomorrow could be different.  :rolleyes:

As far as using 1/8" ply skins over a core-it seemed to work for me.  The roof of the hard dodger I started on is pretty stiff even with no other means of support locking it's shape.  An even smaller piece I had pulled for a seahood is much more demonstrative of the capabilities of 1/8" ply skins.  I actually tried to crack that one but gave up for fear of later regret should I need the part for something else.

Thanks to Steve's input I think 'I have a plan'.  Just wish I could spin my drawings in 3D to really get the point driven home.

Of course this is stolen art!
__________________________________
One thing I've noticed is these pics seem to get compressed horizontally when posted.  Stretch it a bit and it doesn't really look that     punchy or is it       paunchy!

[Steve M]

Hi Tony
If you look at the "Foreigner style" dodger on my blog You'll see pretty much exactly what you've drawn. Although I did this, and later, a couple more in this exact style, in a female mold.
 Bending thin ply, pre glassed and surfaced on the inside with pre made window openings and rebates would work superbly.
This would go equally well for the top , that is finish the glassing on the inside top surface and fill ready for paint, all done flat on a table.
Flip the top over and bond the core to it getting only one surface of the core wet  in the bonding process.
When this combination is bent over a former (say a beefed up frame for a fabric dodger) the uncoated top surface (facing up) opens up naturally.
 Balsa and honeycomb are particularly good for this purpose.
The final top layer of glass/ply are glued down onto it and pulled into firm contact while gluing, using tension able webbing straps.
I only use real thin ply for this combination, say 1/8" each side
Note here, and this is important! for any curved surface like the top of Foreigner or the full wrap face panels your ply needs its main surface grain running in the fore and aft or the up down plane,not around or over.
So you need to cut your ply sheet into sections (across the sheet ) and edge join (small simple scarfed join) the 4ft sections.
 Im having difficulty explaining this, but if you neglect to do this your ply will tend to dish in when you pull it round a curved former.
You will see one of the pictures shows a "Foreigner style" which I built for a Pearson 36'. the mold pictures show the ply wood orientation clearly.
Even thought this was for a female mold the same thing applies .
Steve Marshall

[ebb]

As this thread threatens to sink into the archival marsh, as these threads do as they get pushed down the list...

This is, for some reason, an amazing LIVELY small sailboat site.  

Note that we have had MORE THAN 8000 TECHNICAL POSTS since Bill started counting in this format.  
It's been a fantastic resource for yours truely....and a lota fun  
And I suppose likewise for all the ghosts who whaft through without even saying HELLO.

I personally want to thank you Steve Marshall for coming in to the pub here and joining  the conversation.   Your generous sharing EXPERTISE has helped me fer sure!
Great tips.... THANKS:cool:


......more?........

[Steve M]

Hi Ebb
 Thanks for that comment.
It really is may pleasure to help when I can.
Hard dodgers sort of be came my passion, as I did many miles protected by them and I know they offer the cruiser a huge benefit
 Its hard to describe till you've actually had one in use.
Anyhow good luck with your project,If You get stuck along the way in your  drop me an Email

And if I can, Ill help.

Steve Marshall
Marshall Design
steve.marshall@gmail.com

[CapnK]

My apologies, fellas - I haven't been saying much on the topic, just looking at the pictures, reading the posts, and imagining a dodger as I get in and out of the boat every day.

I have a giant tarp boom tent that I use over the boat in the summer, when shade is needed. This time of year, shade is abhorrent, to a thin-blooded southerin' boy like me, so I use a tiny dodger tarp - about 4' x 4', with a window in it. It sits over the companionway on rainy dayskeeps water from falling straight in. On sunny days, it's easier to peel back. The whole point of mentioning it is that I've been using it to gauge how high a dodger needs to be, for me, to allow ingress/egress, without a conk on the head every time.

To that end, I had this thought:

How about a cutout in the dodger 'roof', right over the companionway, a 'notch for the noggin'? Our dodger needn't be so high, to allow easier passage of a sailors skull. There'd still be rain protection in the cockpit when sitting to one side, and a small cloth flap could be fit to cover the notch if/when needed; it could even have elastic on its after end, so that it needn't be removed when climbing in/out, but would keep water from falling in?

Excuse the high quality drawing, but I hope it conveys the idea.

Steve - have you ever seen anyone do something like this? (And many Thanks! for joining our discussion! )

[CapnK]

The notch-covering flap could also be made of a hard material, larger than the notch by a couple inches, attached (hinged) at the forward edge, with fabric at the sides like a bellows. That way it could go up and down easily when climbing in/out, but wouldn't sag with the weight of rain/spray.

[Tony G]

....boy do I feel stupid....

[Steve M]

Hi epiphany
I cannot remember seeing the cut out as shown. I'm sure it would aid access in a low profile dodger but the trade off would be a loss of strength across the back edge and no continuous aft edge grab rail.
This could be partially offset by creating an up tuning rim around the opening of say 2" depth which would also provide water proof rim to a minor extent.
A thing I have seen on a friends boat, and this was around his center cabin hatch.
A rim of bolt rope type sail track was fastend around the front and sides of his hatch onto the deck.close to the hatch base.
A fabric cover with bolt rope edge and thin battens in pockets was slid into this, that when pushed  up wards by the hatch being opened formed a wedge.
The batten pockets were positioned to line up with the  side edges of the hatch and the batternes supported the fabric over hang that was some 5'' longer than the hatch.
This gave excellent protection from the weather while sailing with the hatch open this same idea might apply to what your suggesting ??
Steve Marshall

[Bill]

The Burns 30 had similar access problems and the fix in the soft dodger was to create a deep U (about a foot wide) in the aftermost tubing with a zippered canvas section that could be flipped back (er, forward).  Don't recall if the bottom (forward end) of the U had a support going forward -- the canvass cover may have been adequate.

[CapnK]

Re: the Burns 30 - There's no such thing as an original idea, is there?

Steve, your friends hatch cover sounds like it would work well. In my original thinking on a 'cover' of some sort for the opening, I was thinking a batten could be placed in the fabric to hold it up.  Bills zipper idea would be workable, too. Heck, I guess the edges of the fabric could be attached with elastic even, just enough to allow your head room getting in and out.

As far as having a 2" lip - that would be a good idea, besides just strengthening the opening. Made to where it goes around the outside edges of the "hard flap", it would serve to keep spray and wind from being able to lift the flap up accidentally.