Another Dodger Project

[RaymondR]

There were a number of things that annoyed me about the dodger which came with my latest boat.

I wasn't to keen on the appearance, it looked sway backed and a bit vertically aggressive on the front end, the flexible clear view stuff had stains which I could not remove, I like to sit in the companionway whilst underway and the side panels were not transparent, there was nothing to grab onto whilst accessing the for deck or returning to the cockpit, and I wanted to mount some more solar panels somewhere and it's top was the only practicable real estate but it was not suitable for mounting them for a number of reasons.

There were a number of options materials wise but I don't like working with sticky and spiky, hairy stuff and had rebuilt the bimini in aluminium and like working with it so alloy it was.

I now have available a SS hooped dodger and the second image illustrates the progress to date.

I got a bit ambitious with the panels so the alloy frame ended up a bit bigger than originally planned but I now have 300 Watts which is 60 more than than the original plan. Also the 2 X 150,s were on sale and ended up being cheaper.

[tkeithlu]

That's areally nice design, Raymond. Thanks for posting it; it gives me ideas for a flybridge.

[Bill O]

Looks good so far and well thought out for hand holds on the dodger.

A couple of quick questions:
How are you going to cover the dodger to make it water/drip proof?
How will you attach the surround on the dodger and to the deck?

Please continue to post progress pics as you go.

[RaymondR]

Originally Posted by Bill O

Looks good so far and well thought out for hand holds on the dodger.

A couple of quick questions:
How are you going to cover the dodger to make it water/drip proof?
How will you attach the surround on the dodger and to the deck?

Please continue to post progress pics as you go.

I will not be using any fabric at all in the new dodger and am at present working on extending the alloy covering over the areas to either side of the solar panels. I will post images when done.

The hand holds were a very significant factor in the decision to rebuild in alloy. I was nervous every time I went forward even when the seas were calm and there was no way to fix any sort of secure rail to the fabric covered dodger. My old boat had high hand rails with the top wire of 1/4" stainless but this one has the more prevalent yachty style low rails with only thin wire and I have no confidence in them. There is a grab rail all along the coach roof but then a big gap where the fabric covered dodger was. No longer a problem.

[RaymondR]

I installed the first of the transitions from the panel mounting rail to the side perspex window today. As can be seen from the attached image the alloy plate has a twist in it.

I did this so that the side profile line tends to more horizontal so that it appears wedge shaped when viewed from the beam. Since I angled the top of the dodger up towards the stern I think it gives a better, rwo part transition to the fairly horizontal line of the top of the coach roof.

The addition of these pieces is also giving a nice cambered appearance to the overall look from forward.

The top of the perspex side window will fasten along the bottom edge of the alloy.

It turned out to be a tricky bit of metal work but I.m glad I went slowly and got it the way I want it.

[RaymondR]

When I started this solar panel business decades ago I purchased two 80 Watt panels at $750 each. Whilst fitting them one of them shattered because the frame was twisted. Whilst panels have become a lot cheaper my paranoia has not at all decreased hence I always protect them from impact damage from below.

I contemplated using a light weight sheet material underneath the panels to protect them including styrofoam with a light FG woven cloth epoxied on to harden it and provide a surface for paint until I realized that all these materials are thermal insulators to some extent and would trap heat between the underside of the panel and the sheeting, hence the alloy sheeting.

This image illustrates the fitting of aluminium sheeting underneath the support frames.

[RaymondR]

The dodger project was interrupted by a wreck when another boat having just been relaunched attempted to wipe of my davit whilst leaving the slip. But we are now ready to start fitting some windows which I collect today.

The bimini panels are usually supported by the davits but in their absence by a halyard.

I have still not decided on what to fill the slot down the middle between the panels with. The candidates at the moment are polycarbonate on an alloy frame hinged at the front with fold down side panels or fabric stretched between the front and the bow at the back.

[Discovery 15797]

Originally Posted by RaymondR

I contemplated using a light weight sheet material underneath the panels to protect them including styrofoam with a light FG woven cloth epoxied on to harden it and provide a surface for paint until I realized that all these materials are thermal insulators to some extent and would trap heat between the underside of the panel and the sheeting, hence the alloy sheeting.

Hi Raymond, it's looking nice.

Obviously you are aware of solar panel output degradation as the heat increases, so I'm confused with the sheet metal panel that will certainly be a insulator.

I also understand your desire to protect the underside of the panel. So, I wonder if you put a couple of slats across the panels and then fastened Phifertex would give you the protection as well as some ventilation to keep your panels a bit cooler. You've probably thought about this, but I'm just asking if you had a different perspective in choosing your design.

[RaymondR]

The thermal conductivity of aluminium is about 240 times that of the glass in the panel so I'm hoping the 1.2 mm alloy will result in a minimal heat retention by the panel. However, I can put a computer fan into the centre of the panel and the air will escape around the edges of the panel which is not sealed.

I went with acrylic rather than polycarbonate for cost reasons. clamped on one side and it does not look to bad.

[Discovery 15797]

Originally Posted by RaymondR

The thermal conductivity of aluminium is about 240 times that of the glass in the panel so I'm hoping the 1.2 mm alloy will result in a minimal heat retention by the panel. However, I can put a computer fan into the centre of the panel and the air will escape around the edges of the panel which is not sealed.

I went with acrylic rather than polycarbonate for cost reasons. clamped on one side and it does not look to bad.

Good idea...I figured you thought about that and had it covered.

I assume you're doing the alum welding yourself???

Can't wait to see the finished product.

[RaymondR]

I had to give up welding a few years ago, too much natural weave.

I was drilling, tapping and screwing perspex on today and wandered forward to take a look and thought, that's a fair bit of windage I'm installing there. So I'm halted whilst I ponder whether or not I should, and how to, make the windows readily removable.

[coopec43]

Originally Posted by RaymondR

I had to give up welding a few years ago, too much natural weave.

I was drilling, tapping and screwing perspex on today and wandered forward to take a look and thought, that's a fair bit of windage I'm installing there. So I'm halted whilst I ponder whether or not I should, and how to, make the windows readily removable.

I notice you live in Cairns (Northen part of Australia) so it is very hot. I think you are wise to have opening hatches/windows for ventilation.

This article may interest you.

"Large opening windows in dodgers should be made compulsory by legislation, any canvas worker building one without such a window and perhaps even removable sides should be banned from the trade".

How to keep cool when sailing in the tropics

http://www.mysailing.com.au/news/how-to-keep-cool-when-sailing-in-the-tropics

[coopec43]

I notice you don't want fabric but what about this dodger? It looks like epoxied fiberglass cloth over a frame.

[RaymondR]

That is a beautiful dodger, one of the prettiest I've seen.

I actually bought a couple of sheets of bending ply to make a female mould to build a glass fibre dodger but decided I hate working with the stuff so much I opted for building in alloy. Looking at that one I'm tending to wish I'd persisted.

A second reason for opting for the alloy construct was I had already done the bimini in alloy and visually the retro industrial look for both dodger and bimini was a bit more consistent.

Also at 6'7" tall and 75 years old I wanted the slot above the companionway and it was structurally easier to do it in alloy. I will be putting a roll up fabric "tunnel" over the slot for rainy weather.

[coopec43]

Originally Posted by RaymondR

That is a beautiful dodger, one of the prettiest I've seen.

I actually bought a couple of sheets of bending ply to make a female mould to build a glass fibre dodger but decided I hate working with the stuff so much I opted for building in alloy. Looking at that one I'm tending to wish I'd persisted.

OMG!! Now you've got me going again with this dodger It would be lightweight and in the event of survival conditions it would be destroyed without destroying the yacht.

Apparently a lot of yachtsmen like to lower the dodger to reduce wind-age in a storm

I also like the Riada ll dodger but I think it would be too heavy and it would be too long because mine is a center cockpit.

And the there's the one they fit to Hallberg Rassy yachts