Tiki 38 - change inboard diesel to outboard electrical?

[Yann & Chantal]

Hi everyone!

We own a Tiki 38 that is equipped with two VETUS M2.13 diesel engines. 12 HP each. Engine and shaft and impeller can be lowered when used. The design is heavy, takes precious space on deck and until recently had no safe holding down of the shaft -> so we ran into some problems when the lowering ropes got tangled up in the propellers.

We would like to upgrade to 2 electrical motors, possibly outboard engines. I have been looking into epropulsion but am open to any better suggestions.

Has anybody tried to electrify a Tiki 38?

What are the pro and cons?

What are the experiences with an electrical engine?

Thanks in advance 

Cheers

Yann

[Jozef De Roos]

sorry that it took so long. But now I can show you something real. The propellor you see is just to try out and see what the impact it has. Allso the energy it takes. I hope I can make this season a few trails. For the motors this is all there is, the electrical stearing has to be developed. The batteries is two times 15 kWh connected together so there is in total 30 kWh. we have build it ourselfs.

[Yann & Chantal]

No worries!

Fantastic Jozef, thanks! It looks very neat, meaning elegant and non-intrusive.

30 kWh sounds quite reasonable. 

Can you say something about the costs? And what motor (brand) did you take?

What do you mean "the electrical steering has to be developed "?

[Jozef De Roos]

At the moment, I do not yet have a clear picture of the total cost. The motors are from Flipsky, and my son wants to first take measurements regarding power consumption and design the propeller based on that so that it can be used most efficiently. This will also allow him to better determine the operation of the motors. I will ask him to tell me a bit more about this in due course.

[Yann & Chantal]

Hi Jozef, 

any news and updated pictures? Please?

We are looking into putting epropulsion engines, either Navy Evo 6 kW or Pod Drive 6 kW. 

We asked for an offer from epropulsion, numbers are around € 12 - 14k depending on the batteries we'll choose.

A lot but maybe doable...

Jozef De Roos said:

At the moment, I do not yet have a clear picture of the total cost. The motors are from Flipsky, and my son wants to first take measurements regarding power consumption and design the propeller based on that so that it can be used most efficiently. This will also allow him to better determine the operation of the motors. I will ask him to tell me a bit more about this in due course.

[Sander de Roos]

Son here:)

I'm looking for pictures, and will probably find some, but usually when I'm there I'm working and forget to take them.

We've looked into Epropulsion as well, and their stuff is great, but like almost all of the current crop of electric boat propulsion products it comes at a steep price. With the pod drives there isn't really a logical place to attach them to the hulls, and they will add substantial drag even when freewheeling. The original outboard design from Wharram fixes this by just not having them in the water when not in use, which I liked and wanted to maintain. Also, most pod designs in the 6kW class use quite fat motors. There's reasons for that, but those reasons apply more to cabin cruisers than to sailing vessels, to whom the motors are not the primary propulsion. 

So, we wanted to maintain the motor stowing capability, and than you're either stuck with outboards, or need to make some kind of adapter pedestal arrangement for a pod motor. The outboards are designed for a different use and don't adapt well to the catamaran usecase, and given their price I thought, somewhat overenthusiasticly, I could do something sleeker for less. Hence the "blade" style tilting motors shown. 

The motor masts themselves are almost entirely made out of fiberglass, using printed fillers to give shape. Getting this to be both minimal drag and strong enough was a bit of a challenge, given that water is quite a bit thicker than air, which as an aerospace engineer is the usual working medium. But, no carbon fiber was used, both for cost, general faff to work with it, but mostly, galvanic corrosion. Using a single hinge (the counterpart to this is just lashed onto the mid bridge beam), and ropes to transmit the drive/reverse forces nicely fit in the whole "rope and sticks" design philosophy of Wharram, I think.  The motors are above the keels, so beaching is still possible, though we haven't tried it yet (with the motors down anyway, the harbour is tidal).

Batteries is where the real cost difference is made. If you look at the cost of bare LiFePo4 cells, there is no way the prices Epropulsion, Torqueedo, Mercury, and many others are charging are reasonable. I get that they need to make their money somehow, and boat stuff is always expensive, but still. The motors are usually not even that badly priced. While mine are cheaper (though Jozef got the family and prototype discount, which he may have regretted at times), they're not going to be orders of magnitude cheaper, and they have the installed base advantage obviously. The batteries are, and they scale better. I think all in all the 30kWh, done in 2 banks of 15kWh, at 48V (ish) nominal comes in at 3-4k€, though I probably wouldn't do it the same way again. Tricky thing with this was not the cells or where to stow them, but the ancillaries around it. We went with 2 completely separate banks for redundancy, getting stuck at sea because a BMS is throwing a fit is unacceptable, but it does present some additional cost and difficulties. Almost all the time though, both batteries are active and linked. They supply up to 500A, but this is never really used. 

Additionally, all other systems are fed by the same batteries, there are no lower voltage ones on board. 2 300W 24V DC-DC converters power all the regular low voltage loads like pump, lights (both nav and house), radio/AIS beacon, fridge and autopilot. 5kW 230VAC is supplied by a Victron inverter, that can also charge the batteries from shore power. This does all the galley equipment like the induction hob, oven, microwave, coffee maker and washing machine. It also does the hot water, at the galley tap and the shower. This was done for expedience, and while it works, it's not a hotel shower experience as it were. 

So far, the boat has been in the water for a couple weeks, and is by no means finished. Next step is the motor control system, which consists of a 3-axis joystick throttle lever, which has an arrangement of leds in it for status and whatnot. At the moment this goes through a very modified Vommax BTX controller, but that's mostly because I used to work there and could get an early prototype. This will, in time, incluide an NMEA 2000 interface so the autopilot and AIS can talk to it, and a remote, which has quickly proven very useful for solo sailing. Other than that, as previously said, the motors have temporary screws on them right now. They work, but the efficiency at higher power is crap and so more thrust can be had, and is needed. 

Performance has been surprisingly good, even with the wrong screws. 650W per motor gives about 5kts. Sadly, due to the screws (I hope), 2kW per motor gives about 6kts. The motors are nominally 6kW, but you never really use more than 3. Current screws are way undersized and overpitched though, so after I fixed the control situation it's time for new ones. This was always the plan, but I've only really been working on this since March and it's just me. I could quite easily make a 100 or 4000 screws, but 1 or 2 is a different ball game, and we're trying to keep costs down. 

The 2 motors also give you low speed maneuvering control, which works, though finicky with the temporary controls. It can pirouette in place, though going sideways needs additional control axis and/or motors. 

Currently, the system is fed almost exclusively by 2 400W solar panels in the cockpit top, that feed through a Victron MPPT converter. Even this late in the year it seems to keep up nicely, though the house load is more the issue than the motors are it seems. Effectively, the boat fuels itself.

In the future, a third motor is planned on the front bridge beam, though this won't be for propulsion, but rather generation by ways of a water turbine. Electrically, this is dead simple and essentially just a copy of the other motors, but the turbine itself is a whole different story. This will require many hours of CFD to get something semi-decent, hence it being on the back burner for now. Epropulsion claim to do this with the drive motors, and so can the ones I made, but the efficiency of using drive screws for this is, to put it very mildly, not great. 

So, to answer the big question, how much does this all cost? To be honest, I would have to take a good hard look at it. Jozef got a great deal, but not if you have to take into account that he had to raise me first. I can in all probability supply ready to tie on motors for less than a 6kW pod drive from Epropulsion, but given that I'm doing this all by myself I can't provide the same level of service. Then again, neither can they because a pod drive is not the same as a complete solution. The batteries are a different story, and this is where the big savings can be, especially for more capacity. The system in Jozefs boat can be upgraded to 60kWh for about 2k€ for instance. 

If you want to just have it all done, for the same system Jozef has, complete and installed, it should be below 30k. Just the motors, control and battery can be half that, but does require some woodwork. 

And, I would highly recommend waiting a bit for the unknown unknowns to show up. The system isn't all that complicated, but it is very early days still and not even finished yet. Having said that, I can't imagine wanting a fuel powered Tiki38. I get that when the design was made there weren't that many other options, but the complexity, fire risk and noise of it all, it just doesn't vibe with the rest of the boat. 

[Yann & Chantal]

Thanks Sander, wonderful details. 

Sander de Roos said:

Son here:)

I'm looking for pictures, and will probably find some, but usually when I'm there I'm working and forget to take them.

We've looked into Epropulsion as well, and their stuff is great, but like almost all of the current crop of electric boat propulsion products it comes at a steep price. With the pod drives there isn't really a logical place to attach them to the hulls, and they will add substantial drag even when freewheeling. The original outboard design from Wharram fixes this by just not having them in the water when not in use, which I liked and wanted to maintain. Also, most pod designs in the 6kW class use quite fat motors. There's reasons for that, but those reasons apply more to cabin cruisers than to sailing vessels, to whom the motors are not the primary propulsion. 

So, we wanted to maintain the motor stowing capability, and than you're either stuck with outboards, or need to make some kind of adapter pedestal arrangement for a pod motor. The outboards are designed for a different use and don't adapt well to the catamaran usecase, and given their price I thought, somewhat overenthusiasticly, I could do something sleeker for less. Hence the "blade" style tilting motors shown. 

The motor masts themselves are almost entirely made out of fiberglass, using printed fillers to give shape. Getting this to be both minimal drag and strong enough was a bit of a challenge, given that water is quite a bit thicker than air, which as an aerospace engineer is the usual working medium. But, no carbon fiber was used, both for cost, general faff to work with it, but mostly, galvanic corrosion. Using a single hinge (the counterpart to this is just lashed onto the mid bridge beam), and ropes to transmit the drive/reverse forces nicely fit in the whole "rope and sticks" design philosophy of Wharram, I think.  The motors are above the keels, so beaching is still possible, though we haven't tried it yet (with the motors down anyway, the harbour is tidal).

Batteries is where the real cost difference is made. If you look at the cost of bare LiFePo4 cells, there is no way the prices Epropulsion, Torqueedo, Mercury, and many others are charging are reasonable. I get that they need to make their money somehow, and boat stuff is always expensive, but still. The motors are usually not even that badly priced. While mine are cheaper (though Jozef got the family and prototype discount, which he may have regretted at times), they're not going to be orders of magnitude cheaper, and they have the installed base advantage obviously. The batteries are, and they scale better. I think all in all the 30kWh, done in 2 banks of 15kWh, at 48V (ish) nominal comes in at 3-4k€, though I probably wouldn't do it the same way again. Tricky thing with this was not the cells or where to stow them, but the ancillaries around it. We went with 2 completely separate banks for redundancy, getting stuck at sea because a BMS is throwing a fit is unacceptable, but it does present some additional cost and difficulties. Almost all the time though, both batteries are active and linked. They supply up to 500A, but this is never really used. 

Additionally, all other systems are fed by the same batteries, there are no lower voltage ones on board. 2 300W 24V DC-DC converters power all the regular low voltage loads like pump, lights (both nav and house), radio/AIS beacon, fridge and autopilot. 5kW 230VAC is supplied by a Victron inverter, that can also charge the batteries from shore power. This does all the galley equipment like the induction hob, oven, microwave, coffee maker and washing machine. It also does the hot water, at the galley tap and the shower. This was done for expedience, and while it works, it's not a hotel shower experience as it were. 

So far, the boat has been in the water for a couple weeks, and is by no means finished. Next step is the motor control system, which consists of a 3-axis joystick throttle lever, which has an arrangement of leds in it for status and whatnot. At the moment this goes through a very modified Vommax BTX controller, but that's mostly because I used to work there and could get an early prototype. This will, in time, incluide an NMEA 2000 interface so the autopilot and AIS can talk to it, and a remote, which has quickly proven very useful for solo sailing. Other than that, as previously said, the motors have temporary screws on them right now. They work, but the efficiency at higher power is crap and so more thrust can be had, and is needed. 

Performance has been surprisingly good, even with the wrong screws. 650W per motor gives about 5kts. Sadly, due to the screws (I hope), 2kW per motor gives about 6kts. The motors are nominally 6kW, but you never really use more than 3. Current screws are way undersized and overpitched though, so after I fixed the control situation it's time for new ones. This was always the plan, but I've only really been working on this since March and it's just me. I could quite easily make a 100 or 4000 screws, but 1 or 2 is a different ball game, and we're trying to keep costs down. 

The 2 motors also give you low speed maneuvering control, which works, though finicky with the temporary controls. It can pirouette in place, though going sideways needs additional control axis and/or motors. 

Currently, the system is fed almost exclusively by 2 400W solar panels in the cockpit top, that feed through a Victron MPPT converter. Even this late in the year it seems to keep up nicely, though the house load is more the issue than the motors are it seems. Effectively, the boat fuels itself.

In the future, a third motor is planned on the front bridge beam, though this won't be for propulsion, but rather generation by ways of a water turbine. Electrically, this is dead simple and essentially just a copy of the other motors, but the turbine itself is a whole different story. This will require many hours of CFD to get something semi-decent, hence it being on the back burner for now. Epropulsion claim to do this with the drive motors, and so can the ones I made, but the efficiency of using drive screws for this is, to put it very mildly, not great. 

So, to answer the big question, how much does this all cost? To be honest, I would have to take a good hard look at it. Jozef got a great deal, but not if you have to take into account that he had to raise me first. I can in all probability supply ready to tie on motors for less than a 6kW pod drive from Epropulsion, but given that I'm doing this all by myself I can't provide the same level of service. Then again, neither can they because a pod drive is not the same as a complete solution. The batteries are a different story, and this is where the big savings can be, especially for more capacity. The system in Jozefs boat can be upgraded to 60kWh for about 2k€ for instance. 

If you want to just have it all done, for the same system Jozef has, complete and installed, it should be below 30k. Just the motors, control and battery can be half that, but does require some woodwork. 

And, I would highly recommend waiting a bit for the unknown unknowns to show up. The system isn't all that complicated, but it is very early days still and not even finished yet. Having said that, I can't imagine wanting a fuel powered Tiki38. I get that when the design was made there weren't that many other options, but the complexity, fire risk and noise of it all, it just doesn't vibe with the rest of the boat. 

[Jozef De Roos]

I have to correct my son in one point. The solar panels are 610 Wp each, so a lot more than the 400 mentioned. 

Yann & Chantal said:

Bedankt Sander, prachtige details.

Sander de Roos zei:

Zoon hier :)

Ik ben op zoek naar foto's en zal er waarschijnlijk een paar vinden, maar meestal ben ik aan het werk en vergeet ik ze te maken.

We hebben ook naar Epropulsion gekeken, en hun producten zijn geweldig, maar zoals bijna alle huidige elektrische bootvoortstuwingsproducten komt het tegen een hoge prijs. Bij pod-aandrijvingen is er eigenlijk geen logische plek om ze aan de romp te bevestigen, en ze zorgen voor aanzienlijke weerstand, zelfs bij vrijloop. Het originele buitenboordontwerp van Wharram lost dit op door ze gewoon niet in het water te laten liggen als ze niet in gebruik zijn, wat ik fijn vond en wilde behouden. Bovendien gebruiken de meeste podontwerpen in de 6kW-klasse vrij brede motoren. Daar zijn redenen voor, maar die redenen gelden meer voor cabinecruisers dan voor zeilschepen, voor wie de motoren niet de primaire voortstuwing zijn.

We wilden dus de motoropslagcapaciteit behouden, en dan zit je vast aan buitenboordmotoren, of moet je een soort adaptervoetstuk maken voor een podmotor. De buitenboordmotoren zijn ontworpen voor een ander gebruik en passen zich niet goed aan voor het catamaran-gebruik, en gezien hun prijs dacht ik, wat te enthousiast, dat ik iets slankers voor minder kon maken. Daarom de "blad"-stijl kantelmotoren die worden getoond.

De motormasten zelf zijn bijna volledig van glasvezel gemaakt, waarbij geprinte vulstoffen worden gebruikt om vorm te geven. Het was een uitdaging om dit zowel minimale weerstand als sterk genoeg te krijgen, aangezien water een stuk dikker is dan lucht, wat als lucht- en ruimtevaartingenieur het gebruikelijke werkmedium is. Maar er werd geen koolstofvezel gebruikt, zowel vanwege de kosten, het algemene gedoe om ermee te werken, maar vooral vanwege galvanische corrosie. Het gebruik van een enkel scharnier (het tegenhanger hiervan is gewoon vastgemaakt aan de middenbrug balk) en touwen om de aandrijf-/omgekeerde krachten over te brengen, past volgens mij goed in de hele "touw en stokken" ontwerpfilosofie van Wharram. De motoren zitten boven de kiel, dus stranden is nog mogelijk, al hebben we het nog niet geprobeerd (met de motoren uitgeschakeld, de haven is getijden).

Batterijen zijn waar het echte kostenverschil ontstaat. Als je kijkt naar de kosten van kale LiFePo4-cellen, is het onmogelijk dat de prijzen die Epropulsion, Torqueedo, Mercury en vele anderen rekenen redelijk zijn. Ik snap dat ze op de een of andere manier hun geld moeten verdienen, en bootzaken zijn altijd duur, maar toch. De motoren zijn meestal niet eens zo slecht geprijsd. Hoewel de mijne goedkoper zijn (hoewel Jozef de gezins- en prototypekorting kreeg, waar hij soms spijt van had), zijn ze niet veel goedkoper en hebben ze natuurlijk het voordeel van de geïnstalleerde basis. De batterijen zijn dat, en ze schalen beter. Ik denk dat de 30kWh, gedaan in 2 banken van 15kWh, bij ongeveer 48V (ongeveer) nominaal 3-4k euro is, hoewel ik het waarschijnlijk niet op dezelfde manier zou doen. Het lastige hierbij waren niet de cellen of waar ze moesten worden opgeborgen, maar de hulpmiddelen eromheen. We hebben voor twee volledig aparte banken gekozen voor ontslag; vastzitten op zee omdat een BMS een woedeaanval veroorzaakt is onacceptabel, maar het brengt wel extra kosten en moeilijkheden met zich mee. Bijna altijd zijn beide batterijen echter actief en gekoppeld. Ze leveren tot 500A, maar dit wordt eigenlijk nooit echt gebruikt.

Bovendien worden alle andere systemen gevoed door dezelfde batterijen, er zijn geen lagere spanningssystemen aan boord. Twee 300W 24V GELIJKSTROOM-GELIJKSTROOMOMZETTERS voeden alle reguliere laagspanningsbelastingen zoals pomp, verlichting (zowel navigatie als huis), radio/AIS-baken, koelkast en autopilot. 5kW 230VAC wordt geleverd door een Victron-omvormer, die de batterijen ook kan opladen via walstroom. Dit doet alle kombuisapparatuur zoals de inductiekookplaat, oven, magnetron, koffiezetapparaat en wasmachine. Hij doet ook het warme water, bij de kraan in de kombuis en de douche. Dit is gedaan voor de snelheid, en hoewel het werkt, is het niet zo'n hoteldouche-ervaring.

Tot nu toe ligt de boot al een paar weken in het water en is hij nog lang niet af. De volgende stap is het motorbesturingssysteem, dat bestaat uit een 3-assige joystick-gashendel, met een opstelling van leds voor status en dergelijke. Op dit moment gaat dit via een sterk aangepaste Vommax BTX-controller, maar dat komt vooral omdat ik daar vroeger werkte en een vroeg prototype kon krijgen. Dit zal na verloop van tijd een NMEA 2000-interface omvatten zodat de autopiloot en AIS ermee kunnen communiceren, en een afstandsbediening, die snel zeer nuttig is gebleken voor solo zeilen. Verder, zoals eerder gezegd, hebben de motoren nu tijdelijke schroeven. Ze werken, maar de efficiëntie bij hoger vermogen is waardeloos en dus kan er meer stuwkracht worden behaald en is nodig.

De prestaties zijn verrassend goed geweest, zelfs met de verkeerde schroeven. 650W per motor levert ongeveer 5 knopen. Helaas, door de schroeven (hoop ik), geeft 2 kW per motor ongeveer 6 knopen. De motoren zijn nominaal 6 kW, maar je gebruikt eigenlijk nooit meer dan 3. De huidige schroeven zijn echter veel te klein en te veel gekanteld, dus nadat ik de besturingssituatie heb opgelost, is het tijd voor nieuwe. Dit was altijd het plan, maar ik werk hier eigenlijk pas sinds maart aan en het is alleen mijn eigen keuze. Ik zou vrij makkelijk 100 of 4000 schroeven kunnen maken, maar 1 of 2 is een heel ander verhaal, en we proberen de kosten laag te houden.

De twee motoren geven je ook controle over het manoeuvreren op lage snelheid, wat werkt, al is het lastig met de tijdelijke bediening. Hij kan ter plaatse pirouette, maar zijwaarts gaan vereist extra stuuras en/of motoren.

Momenteel wordt het systeem vrijwel uitsluitend gevoed door 2 400W zonnepanelen in de cockpittop, die via een Victron MPPT-omzetter worden gevoed. Zelfs zo laat in het jaar lijkt het goed te gaan, al lijkt de huisbelasting meer het probleem dan de motoren. In feite brandstoft de boot zichzelf.

In de toekomst is een derde motor gepland op de voorste brugbalk, hoewel dit niet voor voortstuwing zal zijn, maar voor de opwekking via een waterturbine. Elektrisch gezien is dit heel simpel en eigenlijk gewoon een kopie van de andere motoren, maar de turbine zelf is een heel ander verhaal. Dit zal vele uren CFD vereisen om iets redelijk fatsoenlijks te krijgen, daarom ligt het voorlopig op de lange baan. Epropulsion beweert dit te doen met de aandrijfmotoren, en dat geldt ook voor de motoren die ik heb gemaakt, maar de efficiëntie van het gebruik van drijfschroeven hiervoor is, om het zacht uit te drukken, niet geweldig.

Dus, om de grote vraag te beantwoorden: hoeveel kost dit allemaal? Om eerlijk te zijn, zou ik er goed en grondig naar moeten kijken. Jozef kreeg een goede deal, maar niet als je bedenkt dat hij mij eerst moest opvoeden. Waarschijnlijk kan ik motoren direct leveren voor minder dan een 6kW pod-aandrijving via Epropulsion, maar omdat ik dit helemaal zelf doe, kan ik niet hetzelfde serviceniveau leveren. Aan de andere kant kunnen zij dat ook niet, want een pod-drive is niet hetzelfde als een complete oplossing. De batterijen zijn een ander verhaal, en hier kunnen de grote besparingen liggen, vooral voor meer capaciteit. Het systeem in Jozefs boot kan bijvoorbeeld worden opgewaardeerd naar 60 kWh voor ongeveer 2.000 €.

Als je alles gewoon af wilt hebben, voor hetzelfde systeem dat Jozef heeft, compleet en geïnstalleerd, zou het onder de 30k moeten zijn. Alleen al de motoren, besturing en accu kunnen de helft daarvan zijn, maar het vereist wel wat houtwerk.

En ik zou sterk aanraden om even te wachten tot de onbekende onbekenden verschijnen. Het systeem is niet zo ingewikkeld, maar het is nog heel vroeg en nog niet eens af. Dat gezegd hebbende, kan ik me niet voorstellen dat ik een Tiki38 op brandstof zou willen. Ik snap dat er toen het ontwerp werd gemaakt niet veel andere opties waren, maar de complexiteit, het brandgevaar en het geluid van alles maakt dat het niet samenvalt met de rest van de boot.