Modified Bolger “Idaho” for tourism. Safe Design?

Hello All,

I would like your opinions on my modification of the Bolger Idaho design. As you can see, I´ve extended the roof aft to the transom. And also, extended it forward to create an attractive swept look from the original windshield. I´ve replaced all the original internal features to create two long bench seats on either side of the cockpit/cabin. (I don´t know which to call it. It is roofed, but it´s open to the air. It has no glass, unlike the original design.)


My Modifications


Original



My main concern is over safety, as this will be a commercial vessel for tourism. It is very narrow with a beam of only 5’ 3”. I´m afraid of what might happen if a group of tourists spot a giant sea turtle off the starboard bow and they all suddenly move to the starboard seating, or worse hang out over the starboard rail. Would the boat capsize? I can´t find any displacement info. The local panga boats carry up to 12 people and they are from 29’ to 33’ long. With the same cargo as the pangas (12 passengers and 2 crew), what would happen if the weight was poorly distributed or changed suddenly? It doesn´t have to meet any US Coast Guard regs. It probably wouldn´t even have to meet any Mexican Coast Guard requirements either, as most of this small scale tourism business is handled very informally. Local fishermen are hired by tourist to take them sightseeing or fishing or sometimes they use their boat as a taxi instead of fishing. If any permits were required, they are usually attained by paying the proper fee to the officials who pocket the money and don´t worry about inspections. So, the design doesn’t have to be perfect, I just want to know if it will be stable with the stated cargo, or if it´s too tender for this application. It´s important to note that it will be used in a calm estuary environment and even if it did capsize, the water depth is usually between a foot and five feet (12”-5’) in most of the area.

If you are of the opinion that it can´t carry that many people, then what would be the safe capacity? The plan I have is for an electric solar powered boat, so would the addition of a box keel full of batteries and an electric motor give it enough ballast to carry 12 people?

I chose the Idaho because it seemed to fit the design requirements that I listed in another thread for the boat I have in mind. But, I didn´t receive any ideas or suggestions from this forum because I wasn´t specific enough. So now I´m creating this new thread and trying to specify exactly what I need. If you wish to suggest another design, instead of the Idaho, here´s my list of needs. Or if you wish you may look at this thread and learn much more about the idea and it´s motivations.

http://www.boatdesign.net/forums/boat-design/what-type-design-hull-form-please-see-fotos-48477.html

1. An extremely efficient hull – so as to be able to propel the boat to 3 or 4 knots with minimal electric power.
2. Be able to carry 12-14 people, ten 200 Watt solar panels on the roof, and a sufficiently large battery bank capable of propelling the boat at the stated speed of 4 knots for 4 hours. (the people carrying capacity is flexible, if 14 is just too much, perhaps a max of 10)
3. Extremely easy to build. (Novice youths will be building them in small Mexican fishing villages)
4. Reasonable stable, in protected waters.

Thank you,
Andy

 

At first glance, without having done any calculations, the ship may have two major problems:
- Lower freeboard tan required.
- The boat, with all the people in a band, not be tilted more than 10 ° and, of course, not to put the margin line below the water.
Perhaps, with no more than 12 passengers, it is not necessary to classify it as a passenger boat.

 

With bench seats like that, you have to sit looking between the other passengers to see scenery.

 

What? You made it very dangerous by changing the design ....

OK, add two pontoons .... one each side, raise your freeboard a little.

You can get by with adding just one pontoon, ama, on one side and using the extended weight to balance the boat over all. Buoyancy would keep the float side from going down, and weight would keep the boat from going over the other side.

Have fun, when are you taking us out for a ride?

wayne

 

PS, why don't you use the seats as built in water tight compartments?



Nothing is worse than a sinking feeling.

 

Andy,

Even without doing any stability analysis, this looks like a very dangerous proposal. You are right to question what would happen when (not if, but when) passengers crowd to one side as they are likely to do. This boat may not be adequately stable for such a load even if passengers stay put in their seats. I don't know what the Mexican standards are for such a boat but the USCG would probably not accept it.

 

If it will be a "commercial vessel for tourism" as you state, it will not pass even the most primitive 3 world certification requirements.

You need a professionally designed (and altered or modified) craft, particularity with that much electric propulsion. I think you've dramatically underestimated weights and overestimated range.

 

Andy,

Flat bottom boats can be deceptively unstable when weight shifts to the low side. You intend to make this electric propulsion so you are going to have lots of heavy batteries -mount them securely in a row, down the center, as low as possible. If I was designing the hull I would have a flat keel just as wide as the batteries then angle it up so that the bottom meets the topsides right at the design waterline. This should give you the best stability for the efficient narrow beam and it's not much more complicated than flat. I think you should reconsider your plan to have inexperienced youths building a commercial vessel. Quality control or disaster, it's your choice.

Seating can be used to discourage overloading and weight shifting side to side. Individual seats facing forward -only as many as the max occupancy insures that passengers will self level. Benches down both sides leave the potential to gather on one side or the other.

 

The Idaho, Sneakeasy or Tennessee designs all have an alternative boxed keel plan and this would be the location for the batteries and would address the pounding these things tend to experience. The whole concept with these designs is light weight and low power. If you burden one with a huge battery bank and a ton or more of guests, you've lost the features of the design and it's just a plodding, narrow design, that isn't efficient, nor economical.

 

No problem if you will only have 6 pax (passengers) at a time. There are almost no rules besides what would be found in any boat.

Over 6 pax and there is a stability TEST , where you use sandbags or drums of water to heel the boat.The USCG observes.

When half the free board is underwater thats IT!

IF you want a long skinney boat to carry boodles of pax a cat is the only way to do it.

 

A quick reply.

Tansl,

Thank you. You´re probally right. Please see new drawing with more free board. Discúlpame, no te entendí muy bien de los 10 °. ¿Me dices que, el barco, con todas las personas en una banda juntas al estribor no inclinaría el barco más que 10 °? ¿O, me dices que no debo permitir que el barco incline más que 10 ° con esta banda de gente? Gracias y disculpa mi Castellano. Después de 8 años en el caribe y México, sigo hablando como un indio. Mi Maya es peor.

Andy

SamSam, thanks. I had imagined the people would turn slightly and look forward and behind them, but your right, for a tourist application another seating arrangement would be better. Please see new drawing.

Wayne, you might have been making a joke. But, that´s actually not a bad idea. Change the styling elements from a '20s motor launch to a Mayan outrigger sea canoe. Historically the Mayans in this very spot were the most seafaring of all their civilization. They shipped goods from the original Guatemalan settlements to what is today the state of Veracruz. The light house in this village is built on an ancient Mayan pyramid. Because this is a flat Sandy island, the pyramid was the only high point on which to build the lighthouse.

Andy

Your right about that! The new drawing would have flotation under many on the seats.

 

Displacement? Calculations? Anyone?

Thanks Tom,

I agree with you. That´s why I asked the question. If anyone knows the displacement or has the plans for the Idaho and can help with the analysis, I´d be grateful.

Andy

 

Tropical Sailor, thank you for your efforts in Spanish, you speak very well. I mean, with all the people in a band, the inclination of the boat should not exceed 10 degrees. But this is mandatory only for passenger vessels. Not carrying more than 12 passengers, the ship should not meet this requirement.
In a very crude estimate, the boat must displace around 120 kg per centimeter of immersion.

 

Clarification and more details.

Skyak,

Thank you for your help. That is a good idea to keep the build simple by securing the batteries down the center line for more stability. A simple build is my first priority. But, as I said in my original post;
"If you are of the opinion that it can´t carry that many people, then what would be the safe capacity? The plan I have is for an electric solar powered boat, so would the addition of a box keel full of batteries and an electric motor give it enough ballast to carry 12 people?"
As I said, simplicity of build is very important, but considering the problem of stability, I think the box keel would be worth the extra time and complication to get that ballast down low. PAR had something to say about box keels in his latter post.

As to your comment about the local builders; "you should reconsider your plan to have inexperienced youths building a commercial vessel." I need to clarify something and I hope everyone reading this thread reads this part. Even though I said “commercial vessel”, I meant it in the sense that it will be used to create a small income for someone. Not for me. And not as any type of large business plan. I didn´t go into details again about my background or why I´m volunteering my time in Mexico or why young men will be building this boat, because in a previous thread I explained all of this and no one bothered to read it because it was too long. So if you desire to understand the subject in more detail please read post number 10 of this thread:

http://www.boatdesign.net/forums/boat-design/what-type-design-hull-form-please-see-fotos-48477.html

In that post I responded to a question from PAR. He urged me to be more detailed about what I was doing and what I needed so that he could get a better idea how to help. Unfortunately, the response to that was very long and no one wanted to read it all. (Except for a couple of guys, thanks you guys that did express your opinions) So without going into all the details, suffice it to say that I will be giving a type of seminar/class on boatbuilding to local youths (and anyone else interested) who don´t have many economic possibilities. The purpose is that they can learn to make their own boats, because even though they live in a fishing village many will never have the opportunity to own their own boats and fish for themselves or work for themselves in the tourism industry. Again, all the political and economic and cultural reasons are explained in the previously mentioned thread.

Thank you again for your suggestion about seating. Please see the new drawing.

Andy

Hi PAR,

Thanks for responding. Hopefully you read what I wrote to Skyak about it being a "commercial craft". If not, in post 10 of the following thread I explained it all to you in great detail.

http://www.boatdesign.net/forums/boat-design/what-type-design-hull-form-please-see-fotos-48477.html

To save you from reading it all (it´s long, I know) I´ll just say this. It´s only commercial in the sense that someone will make a wage for themselves from it. Perhaps, it would be better to say “informal economic activity.”

You said, “it will not pass even the most primitive 3(rd) world certification requirements”. Maybe you´re right. But, luckily it would not have to. You´d really have to know more of Mexican culture/customs to understand, but these very poor people don´t get permits to fish commercially. Nor do they get permits to dive for sea cucumbers with crude air pumps and hoses stuck in their mouths. That´s why so many die each year. Nor do they get permits to take tourist who are renting a beach house in their town, out to fish or see the natural beauty that there is here in the mangroves and estuary. Many years ago the locals that had water front (beach front) property sold they plots and simply wood and palm thatched houses to speculators who resold them to foreigners for many times what they paid for them. Now the locals can´t even enter into the gated community that lines their beach. I can get you hard statistics from Mexican fish and wildlife Dept. if you wish, but it´s between a third and a quarter of the fishermen on the north coast of Yucatán that have permits for fish and octopus. When it comes to sea cucumber only 10% of the persons involved actually have permits. The same goes for tourism. In one estuary town the locals have formed a collective water taxi service that commutes to the island beach from the dock in town. That cost 20 pesos per person. They also take the tourist (both national and international) on the tour of the flamingos and anything else the tourist desires. Those costs can go up to about $100 US. They are under no one’s authority but their own. Again, you really need a better understanding of local custom to make a statement like you did, because there are so many laws here that date to the Mexican Revolution (1910) that protect the agrarian based poorest classes. Those laws also apply to “ejidos” on the water (sea or lake or river) and give them broad rights to fishing and agriculture. “Use and custom” in some states supersedes local or federal laws here. Perhaps the best way I can explain it to you would be with an analogy: Think about the Indian reservations in the US. They can make their own laws and have different rights and privileges. That´s probably a good comparison. So to sum up: These, the poorest of the people here, that I´m trying to help, would not be subject to the type of coast guard regs that you have in mind. And if the Mexican Navy, which patrols the beaches to save the giant sea turtles, or the Mexican coast guard ever did bother them, they would simply give the official 50 pesos (less than $5 US) and be on their way. I´m not advocating bribes or corruption in any way. I´m simply stating the facts about how it is here.

About my underestimating the weights and cargo involved, you are probably right. That´s why I came to this fourm. I haven’t even been able to find the displacement of the Idaho. I was hoping you could help me with some of these technical details.

About needing “that much electric propulsion” as you said. I am only considering a 2250 Watt motor. Even then, it would normally be used somewhere between 500 and 1500 Watts, to simply “troll” along letting the tourist enjoy the view.

About your estimates of range: As I explained in my previous answer to you in my previous thread, the maximum range would be about 8km round trip. While the normal trip would be less than 1 km. Probably 700-800 meters. If you want to see the Google maps link I posted of the estuary, please see previous thread. In between trips they would be able to plug into shore power to recharge if necessary, but I doubt it would be, because there is room on the roof for 2 kW of solar panels. That´s enough to satisfy the demand of the motor without using the stored energy in the batteries. And we get a lot of sun here.

I hope I don´t offend you. It is not my intent. On the contrary, I simply want you to have all the facts so that you can better help me with your knowledge and suggestions. I chose the Idaho out of my own ignorance, without the aid of professionals, such as you, in my previous thread. I had to start somewhere and I chose the Idaho because it seemed to me (in my lack of professional knowledge) to meet my criteria of an efficient hull and easy build. But that (my lack of knowledge) is also why I came back to this forum to see if my choice was feasible. As I said in the very beginning of this thread: “I chose the Idaho because it seemed to fit the design requirements that I listed … If you wish to suggest another design, instead of the Idaho, here´s my list of needs.”

1. An extremely efficient hull – so as to be able to propel the boat to 3 or 4 knots with minimal electric power.
2. Be able to carry 12-14 people, ten 200 Watt solar panels on the roof, and a sufficiently large battery bank capable of propelling the boat at the stated speed of 4 knots for 4 hours. (the people carrying capacity is flexible, if 14 is just too much, perhaps a max of 10)
3. Extremely easy to build. (Novice youths will be building them in small Mexican fishing villages)
4. Reasonable stable, in protected waters.

So, if you have a better choice, please share. I also thought about the Tennessee. It´s wider beam could make it more stable, but I think it would be less efficient with its shorter length and wider beam. (Efficacy is important because of the electric application, much more so than if it were gasoline)

One last point. Even though these people won´t be subject to revision like in the states, that doesn´t mean I´m not interested in the safety of the passengers. On the contrary, that´s why I made this thread, so the final design or plan chosen could be safe and simple and cheap for these people to build. If you have any suggestions or plans of your own or of someone else, please advise. Or if you would like to do some pro bono work for this good cause, that would be great. I don´t think you would have to worry about getting sued. That phenomena is not part of Mexican culture. And also, the craft would be operated in no more than 4 or 5 feet of water. Often it would be much less.

Thank you very much,
Andy

I didn´t know that. I knew Bolger liked box keels, but I had no idea he designed one for the Idaho. That´s great becuase if you read my original post in this thread, I said that the addition of a box keel could solve some of the stability problems using the batteries as ballast.

Thanks PAR, hope to hear from you soon.

 

Thanks!

Thanks, I´ll try to do some calcs based on that data and the limited info on the drawing I have.

The rule of under 12 passengers is not a "passenger" vessel sounds great and if that´s the European or Spanish regulation, I´m sure the folks here can get away with it also. But, I fear that in the US they are more strict about number of passengers. It seems like I read (probally on this site) that the limit is 6.

Again, Thank you.

Andy