Stern arch thoughts

[gasdave]

A quick search here hasn't thrown up any easy answer to my question so here we go...

I've been considering the addition of a stern arch to our 37' aft cockpit, mainly for the purpose of placing some solar power in the least shade affected area (a couple of 100W panels) to supplement a wind genny, also not yet purchased. These are as yet very early "plans". I've done the basic calculations for required power and have made the decision to move towards as little dependency on shore power as possible, so that isn't the issue. Battery bank is already suitable size - just need a way to feed it.

What I'm after is some advice/experience of actually designing / sourcing / pricing a reasonable 316 SS arch - in the Glasgow/Greenock area. Searching on the interweb finds lots of welders but most of them are at the industrial/heavy machinery end of the market, not many who look like they've done this sort of thing before. How much might I be looking at for fabrication/fitting? Most of the prices I have found are from forums in the States and are frankly scary money! I'm also aware of the differing opinions about the effect of an arch on boat "balance", although most of those I've looked at appear to lie pretty evenly in the water so I'm not convinced this is a significant factor.

I'm not committed to this route yet - only researching with a view to getting as much out of solar as possible, given the limited footprint. But I would like to rule it out as an option based on sound facts and reliable info from those who have been there before. The other possible attraction is somewhere for davits but I know these can be had for considerably less money without the arch.

Thanks in anticipation again.....

 

[Ric]

If your objective is to "move away from shore power" it sounds like your sailing is orientated towards coastal cruising with the odd night at anchor, rather than making long transoceanic passages. If that is the case, have you first fitted a decent alternator regulator such as a Sterling? With the odd hour a day motoring that you do when coastal cruising - even just getting in and out of an anchorage - a decent alternator regulator will give you 50-80Ah which is way more than you will get with an expensive stern arch, wind generator, solar array, regulators etc.

Just a thought!

 

[neil1967]

Gasdave

I'm in the same position, so I'll be interested in the answers. My preference would be to up the solar to 2 x 200W panels and do without the wind genny, if at all possible. I'm aware it's a significant amount of weight, and I have the added issue that the stern of Vivere is only about 2.4m wide.

 

[Halo]

If you get one fabricated then you need be be really sure that the thing is in 316 and is both passivated and polished (preferably electro polished) before you mount it. Otherwise it will rust, look bad and contaminate the boat with rust.
You may be able to get some materials by buying a used or damaged cockpit tent or spray hood frame from a boat jumble. There are also some vendors of polished tube on ebay. You will still have to polish the welds etc but should make it easier.
There seem to be a lot of old tubs rotting slowly on moorings and perhaps you can get the ok to remove a suitable frame if you can see one

 

[dansaskip]

I reckon a stern arch is definitely the way to go . After much research and thought I designed my own and got a good marine ss fabricator to make it up for me. Cost was about £450, not cheap but worthwhile as with solar panels mounted it makes me independent of shore power and running the engine.

 

[johnalison]

Stern arches I view in the same way as stack-packs. They are both obviously incredibly useful and practical but just look odd. Luckily, that's my problem, not yours.

 

[gasdave]

.....have you first fitted a decent alternator regulator such as a Sterling? With the odd hour a day motoring that you do when coastal cruising - even just getting in and out of an anchorage - a decent alternator regulator will give you 50-80Ah....

You are absolutely right and I have considered this as another modification. I currently have a standard VP arrangement with a 115A alternator so I reckon with a good quality regulator this would speed up charging significantly. However for those times when we might want to lie to anchor or mooring for a couple of days I would eventually need to run the engine just to charge which I'd rather not do if there was a suitable alternative. Also it would be nice to be independent of home marina shore power for charge maintenance when the boat's not being used (cost, galvanic corrosion risk) - I don't have an isolator.

There aren't many yachts with solar power where we are but quite a lot with wind genny's - I'm assuming there's good reason for this. It may be to do with the short winter days and possibility of panels disappearing under snow for days on end when you're not there to check it. On the other hand there is mostly reliable wind. So that's essentially a trade off between more efficient solar power but more available wind power.

Dansaskip - was your £450 in the Carribean? I was expecting well over £1K here?

 

[robertj]

Solar are a lot better than a wind generator unless you spend major money.
The question you have to ask yourself is, do you need to run the engine for hot water if at anchor or do you have a water heater.
Bigger battery banks are good with a big alternator and smart charger.

 

[Tranona]

Wind more popular where you are because... well it is a windy part of the world! Don't think a gantry and big solar panels is the way to go for the usage you describe. Do an audit of your consumption and then look at increasing your capacity to give you, say 3 day's typical usage. Might prompt you also to look at ways of reducing your consumption. Then look at improving your charging if your setup does not keep up. A simple panel for use when not on the boat will ensure that you always start with well charged batteries. Wind might be the next step assuming when you are cruising there is wind to power it. Lots of solar is good in hot sunny places with high demand for things like fridges, particularly if you are living aboard and regularly taking lots out of the batteries, but for short term cruising is overkill (IMHO).

 

[geem]

I really have an issue with the look of stern arches. In addition, when there is a major storm coming you can't easily strip them off. They add a huge amount of windage to your boat that will impact on sailing performance. Why not add panels to guard rails? We had 120w on our last boat that ran everything. 200w seems excessive if you are on
Y coastal sailing in UK. I wouldn't even bother with wind if you have the solar. I have a wind turbine but its output compared to solar is not great and they are noises and unsightly. Al my opinion and entirely up to you in terms of appearance. If you have a beautiful boat don't spoil it. If it's ugly go right ahead!

 

[Ric]

You are absolutely right and I have considered this as another modification. I currently have a standard VP arrangement with a 115A alternator so I reckon with a good quality regulator this would speed up charging significantly.

Don't even think about getting an arch and solar if you haven't first got a Sterling! If you have a 115A alternator, then you can easily install up to about 400Ah of batteries and charge them properly with very little engine running. 400Ah of battery will keep you going for 2-3 days with fridge, TV lights etc.

Also, have you got a decent battery monitor (e.g. NASA BM-1)? Without a battery monitor you won't be optimising your battery usage anyway.

My advice, in this order:
1. Fit battery monitor so you know what you are using and charging.
2. Fit Sterling
3. Increase battery capacity to about 400Ah

You will probably find you don't need solar or wind with the program you appear to have. If you really do need an additional source, look at a wind-genny on a pole and deck mounted flexible panels.

Don't get a stern arch until you REALLY need it. They cost masses of money, add loads of weight and windage, are ugly and unnecessary on a coastal boat. Having said that, I really like them on certain types of boats and for certain programs.

 

[chrisb]

I went through this when fitting out for my circumnavigation . The usual arches were heavy and very expensive . My sailmaker solved the problem for me . I was fitting a bimini and was concerned that it might not be strong enough to leave up in heavy weather . He suggested that it would be and that we add an extra arch to carry arials and the solar panel . This after 36000nm has been well tested, works, has stood up to all conditions encountered during Atlantic and Pacific crossings . Inexpensive and it also looks good .

 

[NormanS]

I sail on the West Coast of Scotland, and never have shore power, when the boat is in commission during the summer. I have a large battery bank of 680ah, an Adverc, and a wind generator. No shortage of power this "summer". It depends on where you are, and your type of sailing.

Solar works out cheaper, but that's small compensation if the sun doesn't shine.

 

[geem]

when the sun doesn't shine my 460w of solar gives 4 amps but not at night!

 

[Sandy]

The more I read about hydrogenation the more I like it and no need for an arch, if you only want to pop a wind jenny and some solar panels on it.

 

[Stooriefit]

Gasdave,

You might want to try Silvers yards at Rosneath as they certainly used to have an onsite SS welder who could make parts up. Also there used to be a chap that was former Faslane welder who did bespoke SS manufacturing based in Rhu - he did advertise on the web but a quick search didn't find him, although a more detailed one might.

 

[Concerto]

Seascrew do some adjustable radar arches that may be suitable for under £400
https://www.seascrew.com/browse.cfm...BULAR-RADAR-ARCHES---ROLL-BARS--&l=0000000902

 

[GrahamM376]

Yes, gantries are ugly but are the best way to mount tilting solar, a wind generator and, use as davits Our DIY one is made from 40 mm tube and cost around €400. Although Sterling or Adverc are good, I don't like running the engine at anchor or on a mooring for a week or two, just to charge batteries. However, if you tend to motor often then one of those plus a larger house bank is most likely the cost effective way.

 

[Halo]

The more I read about hydrogenation the more I like it and no need for an arch, if you only want to pop a wind jenny and some solar panels on it.

What do you mean please ??? Hydrogenation is a process related saturated fats in food !!

 

[dansaskip]

Dansaskip - was your £450 in the Carribean? I was expecting well over £1K here?

No it was in North Wales