Next Boat Design

[N4061]

Hello all, it's been a while since I have posted on TF but thought this new thread would be fun and of some interest. A quick recap of who we are (John & Maria) includes a lifetime boating starting on the east coast then transitioning to southern California. Smaller boat eventually gave way to our first Nordhavn in 2005 followed by another one in 2007 then a break before out third boat around 2014. Then worked with Scott at Helmsman trawlers on a few enhancements to the 38 that was designated the 38E (great boat) we built with a custom salon interior. Then took up sailing and purchased a small 16' Cat Boat from Marshall Marine in Maine I used to learn how to sail. Then I decided to own a true wood boat and commissioned Cottrell Boat Builders in Main to build a semi-custom 11' rowing dingy I still use today for exercise. Then decided to design my own boat with Paul Gartside that he built. I received this boat a few months ago and enjoying cruising the harbors (see story under wood boats). A few folks on TF know I enjoy the planning and building process as much as using boats so no surprise I'm starting work on the next boat. While we are still considering another production trawler nothing has come up that checks all the boxes, so I have started drafting up another custom boat.

First step is defining how we plan to use the boat or its mission which is still being debating between Maria and myself, but we know it's not going to be a long-range boat. Rather something I can single handle and use for local coastal cruising. Possibly have the boat shipped to the east coast for the ICW but time will tell. Preliminary LOA about 35' with a nice beam for maximum interior space for two people. Single level, no flybridge, FD hull design but considering a modified FD for slightly higher speeds and shorter trip durations but this impacts type of power. Easy on / off boarding on port, starboard and transom, swim platform, dingy storage on top with davit. I'm a big fan of simplicity and KISS concept when it comes to boats which is one reason I like my rowing boat so much. The ease of launching and rowing her for an afternoon through the marina to bay to ocean with everything I need inside a carry-on bag is simplicity at its best. When I weigh the enjoyment or fun factor against the cost / hassles / stress of larger boats nothing comes close - at least for me at this time in my life. Trying to replicate or carry this logic into a larger boat is the going to be the challenge as we start planning but should be fun. Fortunately, we have the electric launch to use as a steppingstone and provides some level of confidence we may be on the right track. I'm more than pleased with the all-electric power source and overall simplicity of the system we selected. The new boat will require some type of battery charging but again need to find the proven and reliable source. I'm also considering sail as possible "get home" power source depending on hull design and if we can do some modeling to prove it would even work. More on how we hope to pull this off later in the journey.

I should add that current with developing the plans for this boat I'm working with Paul on another small rowing / sailing dingy. While I'm not interested in sailing as a full-time hobby or method of coastal cruising, I do miss the "fun" part and want to build something I can use for rowing and occasional sailing. I picked up a newly released book by Roger Barnes focused on these types of boats and learning a lot. One amazing story includes two guy who took a 17' through the north passage in 2010 and survived to write about it. Talk about simplicity and long-range adventure! What I'm learning is while motor-sailors struggle to perform both means of travel efficiently doing this in smaller rowing boat is more challenging. Hopefully what I learn from this project will help with the larger boat.

Thats enough with the introduction and I will open this up to anyone who would like to share their thoughts on "what type of boat" they would design and build for similar purposes or mission. I'm mostly interested in real life experiences with focus on what worked and what did not work. Fun stuff.

John T.

 

[Ithaka7]

Hi John - very interesting and off the beaten path ideas. I believe you are asking if electric propulsion makes sense for your next boat. I think it does, mostly because LFP batteries are so cheap now, approaching $60/kWh for the cells. I would say, target 300 kWh installed $20k and a weight of 4,000 lb. This is for the cells only. Now you need to add the enclosure, the cooling/warming system, and the motor (s). May be another 2,000 lb and a good deal of money. I estimate 300 kWh will give you 12h of motoring at 6.75 knots = 80 nm which should be ideal for you. If you need more range, reduce the speed. Everything else on the boat will become much simpler.

I would not worry much about charging at this point. Just charge from port to port, using car style DC chargers (they are beginning to appear in the marinas) or overnight on the slow chargers.

 

[N4061]

Hi John - very interesting and off the beaten path ideas. I believe you are asking if electric propulsion makes sense for your next boat. I think it does, mostly because LFP batteries are so cheap now, approaching $60/kWh for the cells. I would say, target 300 kWh installed $20k and a weight of 4,000 lb. This is for the cells only. Now you need to add the enclosure, the cooling/warming system, and the motor (s). May be another 2,000 lb and a good deal of money. I estimate 300 kWh will give you 12h of motoring at 6.75 knots = 80 nm which should be ideal for you. If you need more range, reduce the speed. Everything else on the boat will become much simpler.

I would not worry much about charging at this point. Just charge from port to port, using car style DC chargers (they are beginning to appear in the marinas) or overnight on the slow chargers.

Thanks for your input which aligns with our preliminary thinking. We learned a little about cooling the batteries on the launch build and discovered additional forced air ventilation was required during sea trials. Fortunately, it was an easy fix. I'm planning to use the batteries ballast and install them low in the boat. I'm still looking at hybrid systems but prefer simplicity which makes "batteries only" our desired approach. Desiring a larger beam over long and narrow hulls will push towards full displacement or slightly modified FD if we need a few extra knots of speed. I'm still learning the efficiency numbers and range on the open launch as our baseline to scaling up to the next boat. Fun stuff.

 

[IfItsWorthDoing]

Hello all, it's been a while since I have posted on TF but thought this new thread would be fun and of some interest. A quick recap of who we are (John & Maria) includes a lifetime boating starting on the east coast then transitioning to southern California. Smaller boat eventually gave way to our first Nordhavn in 2005 followed by another one in 2007 then a break before out third boat around 2014. Then worked with Scott at Helmsman trawlers on a few enhancements to the 38 that was designated the 38E (great boat) we built with a custom salon interior. Then took up sailing and purchased a small 16' Cat Boat from Marshall Marine in Maine I used to learn how to sail. Then I decided to own a true wood boat and commissioned Cottrell Boat Builders in Main to build a semi-custom 11' rowing dingy I still use today for exercise. Then decided to design my own boat with Paul Gartside that he built. I received this boat a few months ago and enjoying cruising the harbors (see story under wood boats). A few folks on TF know I enjoy the planning and building process as much as using boats so no surprise I'm starting work on the next boat. While we are still considering another production trawler nothing has come up that checks all the boxes, so I have started drafting up another custom boat.

First step is defining how we plan to use the boat or its mission which is still being debating between Maria and myself, but we know it's not going to be a long-range boat. Rather something I can single handle and use for local coastal cruising. Possibly have the boat shipped to the east coast for the ICW but time will tell. Preliminary LOA about 35' with a nice beam for maximum interior space for two people. Single level, no flybridge, FD hull design but considering a modified FD for slightly higher speeds and shorter trip durations but this impacts type of power. Easy on / off boarding on port, starboard and transom, swim platform, dingy storage on top with davit. I'm a big fan of simplicity and KISS concept when it comes to boats which is one reason I like my rowing boat so much. The ease of launching and rowing her for an afternoon through the marina to bay to ocean with everything I need inside a carry-on bag is simplicity at its best. When I weigh the enjoyment or fun factor against the cost / hassles / stress of larger boats nothing comes close - at least for me at this time in my life. Trying to replicate or carry this logic into a larger boat is the going to be the challenge as we start planning but should be fun. Fortunately, we have the electric launch to use as a steppingstone and provides some level of confidence we may be on the right track. I'm more than pleased with the all-electric power source and overall simplicity of the system we selected. The new boat will require some type of battery charging but again need to find the proven and reliable source. I'm also considering sail as possible "get home" power source depending on hull design and if we can do some modeling to prove it would even work. More on how we hope to pull this off later in the journey.

I should add that current with developing the plans for this boat I'm working with Paul on another small rowing / sailing dingy. While I'm not interested in sailing as a full-time hobby or method of coastal cruising, I do miss the "fun" part and want to build something I can use for rowing and occasional sailing. I picked up a newly released book by Roger Barnes focused on these types of boats and learning a lot. One amazing story includes two guy who took a 17' through the north passage in 2010 and survived to write about it. Talk about simplicity and long-range adventure! What I'm learning is while motor-sailors struggle to perform both means of travel efficiently doing this in smaller rowing boat is more challenging. Hopefully what I learn from this project will help with the larger boat.

Thats enough with the introduction and I will open this up to anyone who would like to share their thoughts on "what type of boat" they would design and build for similar purposes or mission. I'm mostly interested in real life experiences with focus on what worked and what did not work. Fun stuff.

John T.

Hi John - the outline you present appears to overlap significantly with our own boat project. While living in Europe not North America many of the planning considerations may still apply - we chose to start with the smallest cruising catamaran on the market (Broadblue 346) which has the unique advantage of being narrow enough in the beam to fit through the French canal locks (thereby allowing inland transit from the North Sea to the Mediterranean) and also into most monohull berths.

My wife is mobility impaired and does not have ‘sea legs’ as such, hence the need for a very stable boating platform. The BB346 is a sailing yacht by default and ours was the first motor trawler variant, built with certain hull shape alterations and intended from the get-go to operate with fully solar electric propulsion (albeit including a gen set and a kite sail).

The build has been protracted and is not yet completed, so we are not in a position to give you user feedback. The BB346 is not available in North America, but no doubt a comparable design (say the FP MY4) could readily be converted from diesel to electric (or hybrid) propulsion …

 

[DDW]

I estimate 300 kWh will give you 12h of motoring at 6.75 knots = 80 nm which should be ideal for you. If you need more range, reduce the speed. Everything else on the boat will become much simpler.

I would not worry much about charging at this point. Just charge from port to port, using car style DC chargers (they are beginning to appear in the marinas) or overnight on the slow chargers.

300kWh would require 170A at 220V to recharge overnight (8 hours) if everything is 100% efficient. Not sure you are going to find that outlet on the dock at many marinas.

 

[Mako]

Even if you plug into a 50A 240V outlet at the marina, in reality you'll be pumping about 9.6 kWh into your battery bank. So if you're topping off 50% it would take about 16 hours to charge. Call it 24 hours with house loads. That's doable. Very-local coastal cruising.

Definitely carry a diesel generator sized for hybrid propulsion though.

 

[N4061]

After talking with a few builders who provide design services and further discussion on the boats mission we decided to pass on all electric power. I knew starting this project it would be a struggle balancing a simple system installation against the boats mission and I was right. While a more complex hybrid electric power system could get us there, I'm not interested in "developing or proving out systems" on this project. We are now back to weighing the pro's & con's of an inboard diesel against twin outboards (never thought I would say this). Since the boat will be small (under 34') we have options and the thought of cruising in the mid to high teens is intriguing and something we have not experienced in 30 years. We hope to down select a builder within the next few weeks, enter into a contract for Phase I concept study focused on the style of the boat before getting serious on an actual design (Phase II). Since we are trying to blend different styles of boats in a small LOA I'm not sure if we can achieve our desired look. Fun stuff.

John