Topics

Davits & solar panels

David Crisp
 

Hi All,
I'm fitting davits and ~900W of solar panels to an Amel 54.
 
I've had the good fortune to be able to pick up a pair of secondhand Simpson S300 electric davits (SWG 300kg). My contractor here in France has reasonable experience of Amels and is proposing to mount the solar panels directly on top of the davits - i.e. the davits will take 100% of the load. 
With a Highfield 290 RIB (aluminium) plus Honda 15HP OB I estimate the total weight of dinghy, motor, misc, solar panels will come in well under 300kg - the rating of the davits.  I'm not an engineer, so please excuse this if it's a bit dumb, but I'm a little nervous about placing all that load on the base of the davits/hull. Specifically, whilst clearly the davits will take the load it's more where they are mounted on the stern of the boat I'm bothered about.  At the risk of falling foul of "don't buy a dog and then bark yourself" I'm wanting to validate the opinion of my expert'. Bottom line it is my boat and my responsibility. So.... any experience others have had or comments?

Scott, SY Tengah, I notice you built quite a complex structure on Tengah.  You've got a couple of uprights going directly onto the hull as well as a couple onto the davits. Was this because of something you learned, the yard not being quite so knowledgeable or maybe because your davits have a lower SWG rating?

Best, David
SY Wilna Grace

Sv Garulfo
 

Hi David,

On Garulfo we decided to have the front legs going to the toe rail. 

I don’t think the bandwith here will allow me to send pics but there are a few where you can see details on

There was also a post by Dean Gillies on sept 28th 2017 on the Amel Yacht Owners Facebook group about the same subject with some useful contributions.



Best,

Thomas 
GARULFO 
A54-122
Rangiroa, French Polynesia 


On Tue, 1 Oct 2019 at 02:20, David Crisp <david@...> wrote:
Hi All,
I'm fitting davits and ~900W of solar panels to an Amel 54.
 
I've had the good fortune to be able to pick up a pair of secondhand Simpson S300 electric davits (SWG 300kg). My contractor here in France has reasonable experience of Amels and is proposing to mount the solar panels directly on top of the davits - i.e. the davits will take 100% of the load. 
With a Highfield 290 RIB (aluminium) plus Honda 15HP OB I estimate the total weight of dinghy, motor, misc, solar panels will come in well under 300kg - the rating of the davits.  I'm not an engineer, so please excuse this if it's a bit dumb, but I'm a little nervous about placing all that load on the base of the davits/hull. Specifically, whilst clearly the davits will take the load it's more where they are mounted on the stern of the boat I'm bothered about.  At the risk of falling foul of "don't buy a dog and then bark yourself" I'm wanting to validate the opinion of my expert'. Bottom line it is my boat and my responsibility. So.... any experience others have had or comments?

Scott, SY Tengah, I notice you built quite a complex structure on Tengah.  You've got a couple of uprights going directly onto the hull as well as a couple onto the davits. Was this because of something you learned, the yard not being quite so knowledgeable or maybe because your davits have a lower SWG rating?

Best, David
SY Wilna Grace

David Crisp
 

Thanks Thomas,
Can you tell me anything about your solar system - panels, controller etc. please?
I'm looking online at lots of different panels, the choice seems endless!

Best 
David 
SY Wilna Grace

SY STELLA
 

Hi David,
The choice is indeed endless.

The structural decisions you make will go a long way to determine the power rating you end up with. Larger heavier panels mean more power, but you need to consider the mounting structure carefully, particularly if you are hoping to mount onto the davits. (as I did) My three panels weigh around 50kg, my stainless tubing weighs about 15kg. 
This weight is not supported at the lifting points of the davits, and so can likely be deranged when comparing to the 300kg weight limit.
I have a 45kg dinghy and 28kg outboard motor.
I am quite happy with these numbers.

Dealing with the non-mechanical factors... 
The key things are reliability, efficiency, access to data and of course safety.

I used the Victron MPPT solar controller with bluetooth interface.  Victron is a reliable brand, (most would agree), and the BT interface gives good access to the system data and allows control without needing access to the hardware.
The Victron unit is efficient, and regardless of brand you choose, you must get an MPPT controller for efficiency. 
Serial or parallel connection is a ubiquitous debate. In a perfect environment, serial connected panels are more efficient due to lower power loss in the cabling and also require lighter (cheaper) cabling due to lower currents (higher voltage).  However, series connected panels are degraded much more by partial shading of the panels.  This is a choice you must decide upon. I chose parallel. 
To tick the safety box you need to make sure you have good quality, properly rated breakers on both battery and panel connections. Properly sized cable with good quality interconnections is also critical.

I used 3x 240W Panasonic HIT panels.

Feel free to ask any specific questions you might have along the way. Good luck.

Dean
SY Stella
A54-154


Sv Garulfo
 

Hi David


See the post:
for an overview of our electrical setup and for more details of the panels:

Hope that helps


Best 
Thomas
GARULFO 
A54-122
Fakarava, French Polynesia 


On Thu, 3 Oct 2019 at 10:42, SY STELLA <stella@...> wrote:
Hi David,
The choice is indeed endless.

The structural decisions you make will go a long way to determine the power rating you end up with. Larger heavier panels mean more power, but you need to consider the mounting structure carefully, particularly if you are hoping to mount onto the davits. (as I did) My three panels weigh around 50kg, my stainless tubing weighs about 15kg. 
This weight is not supported at the lifting points of the davits, and so can likely be deranged when comparing to the 300kg weight limit.
I have a 45kg dinghy and 28kg outboard motor.
I am quite happy with these numbers.

Dealing with the non-mechanical factors... 
The key things are reliability, efficiency, access to data and of course safety.

I used the Victron MPPT solar controller with bluetooth interface.  Victron is a reliable brand, (most would agree), and the BT interface gives good access to the system data and allows control without needing access to the hardware.
The Victron unit is efficient, and regardless of brand you choose, you must get an MPPT controller for efficiency. 
Serial or parallel connection is a ubiquitous debate. In a perfect environment, serial connected panels are more efficient due to lower power loss in the cabling and also require lighter (cheaper) cabling due to lower currents (higher voltage).  However, series connected panels are degraded much more by partial shading of the panels.  This is a choice you must decide upon. I chose parallel. 
To tick the safety box you need to make sure you have good quality, properly rated breakers on both battery and panel connections. Properly sized cable with good quality interconnections is also critical.

I used 3x 240W Panasonic HIT panels.

Feel free to ask any specific questions you might have along the way. Good luck.

Dean
SY Stella
A54-154


David Crisp
 

Thanks Thomas,
Excellent info' and lot's of reading.  Really grateful for being able to benefit from your's and others experience and path finding. Thank you.

David
SY Wilna Grace