How far will 'Natural High' go under battery power alone?

I don’t know the answer to this but it is not really important for me as I don’t intend to use the motors very often other than maneuvering in harbors or anchorages. However, it is likely that I may use the electric motors to improve sailing performance from time to time…so long as I can’t hear them.

Anyway here are the figures about how long they could be run for.

Batteries – 8 x 6 volt Trojan 105’s,
Total capacity of battery bank – 225 Amp hours (at 48 volts)
Usable amps at 50% discharge – 112.5 Amp hours.

According to Kevin at Re-e-power the draw on the battery bank would be a total of 30 amps for both motors. I questioned Kevin on this because his website indicates a much higher draw. He explained that the higher figures were at the motors not at the batteries. Don’t fully understand that but I will accept what he says as he is the expert.

So, this would relate to 3.7 hours cruising on battery power alone which is more than I was expecting from this size battery bank. Whilst motor sailing the draw would be even less!

I will be putting on as many solar panels on the boat as I can fit so I can minimize the amount of time I will need to run the generator.

Also, these electric motors will also regenerate at a reasonable rate. For example, if you used the motors for say 15 minutes to get clear of an anchorage and then hoisted the sails and started sailing with the motors off it would only take an hour and a quarter of reasonably brisk sailing to top up the amps in the battery bank that had been used during the 15 minutes earlier.

So, I figure that taking this into account along with the solar panels and the genset which would have enough fuel for 40 hours I will have plenty of capacity for even extended cruises.


Will the weight of a genset and extra batteries be to much?

I have had a number of people suggest that it is not a good idea to put a genset in a Tiki 38 because gensets are so heavy and it is important to keep weight to a minimum.

At first glance it would appear that this is a valid concern…but, is it really? Let’s look at the figures which are now very important given that I have decided to use electric motors.

Firstly, consider the relative weights if I was NOT having a generator, a water maker and was powering ‘Natural High’ with 2 x 15hp outboards.

1.Without genset

House Batteries (4 of) - 112kgs
Outboard motors – 2 x 46kg – 92kgs
Starting batteries – 2 x 12kg – 24kgs
Fuel – 80 liters – 80kgs
Outboard motor housing and hinges etc – 25kgs
Enough fresh water for a reasonable cruise – 300 liters = 300kgs

TOTAL – 633kgs

2.With genset, electric motors and water maker.

House batteries (8 x 6V Trojan 105’s) – 224kgs
Genset – 80kgs
Starting battery – 12kgs
Exhaust system, filters and piping – 20kgs
Genset fuel – 40 liters – 40kgs
Electric motors -2 x 26kgs = 52kgs
Controllers – 2 x 8kgs = 16kgs
Cabling – 12kgs
Water maker - 30kgs
Water reserve 88 liters – 88kgs

TOTAL – 574kgs

Under this scenario Option 2 with the genset, extra batteries and water maker is actually lighter. Of course option 1 could be reduced in weight by cutting back on the house batteries and carrying less water which is no doubt an option for those people who are happy to shower in salt water…but, I like to go to bed after having a good fresh water shower.

I am also going to have an electric outboard for my tender so there will be further weight savings. It will also mean that I don’t have the inconvenience of either carrying petrol or having to get it.

The balancing of the weight should work out well as most of it will be close to the center of buoyancy. The forward port cabin will house the genset against the aft bulk head. There will be no accommodation in that cabin.


Creed's boat is one step closer to the water!

Creed O'Hanlons Tiki 38 Admad Bin Majid was today transported from one of Raoul's boat yards where is has been since construction began, to the smaller older yard where my boat is being constructed.

It will be there for the rigging set up prior to launching hopefully sometime next month.  The last 9 months has no doubt been very frustrating for Creed as he has been incapacitated for a great deal of this period which brought progress to a crawl (at Creed's request).  

One of the advantages of building a custom boat is that you can have what you want.  On the other hand it can be a two edged sword if for some reason you are unable to spend the time and visit the yard in order to be able to convey exactly what you want.

Hopefully Creed's health is back to normal and that his boat will be able to be finished and he can embark on the adventures that he is so looking forward to.  I also hope to join him in one of his remote locations at a later time.  Creeds blog can be found by clicking here. 


I have made a Decision...

To go all electric power!

Instead of using the 2 x 15hp Honda outboards I had originally planned 'Natural High' will have a pair of E-Pod 3000's.

I have researched them thoroughly and spent an hour or two on the phone with Kevin Plank of Re-e- power in the US and I feel comfortable that this is the way to go.

I have also decided to buy the genset which Kevin can also supply.  As I noted in an earlier post I was intending to buy an Australian built genset but, the advantage with Kevins genset is that it is already set up with a 48 volt alternator and has a sound shield.  There is a possibility with this genset that I may be able to  have it set up so I can hardly hear it running.

In my last boat which was a 76' power catamaran I had 2 x 12kw AC Fischer Panda generators and it was difficult to know that they were running unless you looked at the guages.  However, I had reliability problems with them which is why I am not using one now.  They may have sorted out those issues by now (it was over 10 years ago) but I don't want to take the risk.  From the data that has been provided this genset should be as quiet as the Fischer Pandas.

I have been asked, what about the extra weight because of the additional batteries...and also how long will it go for under electric power from the batteries alone.  I will do a separate post covering these issues as the theoretical results are quite surprising.


More Electric Power options...

The big benefit in having a blog like this is that readers are willing to help with their input.  A reader called Roger was kind enough to email with some URL's that he thought I would be interested in. 

One of them had marine electic motors but unlike the ones mentioned in my previous post these would be fitted permanently in the water under the hulls.  This has tremendous appeal in that it would not be necessary to raise and lower the units...and would remove the potential for waves hitting the housing of the outboard motors.

I have written to the manufacturers and will call them tomorrow and then investigate if these will be a viable option.


Electric Outboards?

My friend Creed O'Hanlon whose Tiki 38 inspired me to proceed with my build in Thailand sent me a link the other day from a friend of his in Germany.  It was about a new electric outoard.  A larger one than the picture. 

Apparently these new ones are equivilent to about a 9.9HP petrol outboard.  The company that produces them has not got any details on their website as yet but I am hoping to get some info shortly.

It seems quite interesting.  I figure that they may be an option because they are lighter than petrol outboards and there is no fuel required.  This weight saving may well offset any increase in the size of the battery bank.  In fact, in my case it may even save weight as I am having a good sized battery bank to power a little air-conditioning unit in any case.

I intend having a LOT of solar panels so I only need to use the DC genset minimally.

I have still got to do all the calculations and get all the info together.  I'll let you know when I know more.

I haven't discussed it with Raoul as yet as he was out sea trialling a new 60' vessel they have just recently launched.


The fairing continues...

Its a big job and its progressing well.  But, I suspect that there is still a good few weeks to go before it will be at a stage where I could say it is as good as it gets.  I don't mind as there is a lot of work for me to do to ensure that they have full instructions on the interior fit out etc.

I am making an effort to stay in front of the workers so there are no mistakes and this avoid the frustration which everyone feels when work have to be, good.

These are the latest pictures that I took today.



What height to put the main berth?

I have had to do a bit of playing around with this.  It seems that the height called for in the Wharram plans only allows for a reasonably thin squab.  But...I want at least a 150mm thick innersprung mattrass so I figure it needs to be lowered a bit.

Adding to the complications is that I want to fit an 88 liter Vetus water tank underneath the berth at the foward end.  But...the tank is 800mm wide and it would have to be raised onto a shelve it is is to go across the hull.  Then that was going to present a problem if if I wanted to lower the base of the berth to allow for the thicker mattrass.

So, after scratching my head today I decided to run the water tank fore and aft.  It means a little less storage under the berth but at least there will be adequate clearance above the tank.

I have been asked why a Vetus water tank when I could have one built in glass or stainless a lot cheaper?  Well the short answer is that I really like pure untainted water and that is just not possible from a built in tank of stainless or glass.  The Vetus tanks are built specifically for water and they guarantee that the water is odourless.