Shanty boat build - self design BBC materials

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jbo_c
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Re: Shanty boat build - self design BBC materials

Post by jbo_c »

Yeah, but a 40 is a big bump in largely protected water with a .3mph current flow. I just think we get obsessed with bigger for the sake of bigger sometimes

For instance, I’m still struggling with building this boat at 22’ rather than the 20’ I originally planned. 2’ isn’t much, but do I really NEED it?

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Re: Shanty boat build - self design BBC materials

Post by silentneko »

It's not really bigger for the sake of just being, it's an efficiency of machinery too. Can it move with a 10hp, yes, but will it move against wind and current, maybe. However at what RPM? If you are running a small motor near WOT just to move at non planing speeds it will burn a lot of fuel, foul, and have a short life cycle. Since you only have a single motor you have to protect its reliability and serviceability.

Many times you can get better MPG out of a larger motor at half throttle, and longer life, then a smaller motor at higher RPM. And you have reserve power. 40hp may be overkill, but as you go up in motor class you also get better torque and much better prop selection or lower unit choice.

Also look at the motor class. For instance the 40-50-60hp motors mostly use similar blocks, so I went with the 60hp over the 50 for my FS. It added no weight, a 20% bump in power, and helps when we load down the boat for scalloping trips.

Most 9.9's are the limit of that class. 15hp is typically the same as 20hp, same with 25-30hp.

As far as 2ft bigger goes, I've never heard anyone say I should have built my boat smaller, lol. You never heard of 2ft-itis?
Built: 15ft Skiff, 16ft Skiff, Modified Cheap Canoe, and an FS17.

Matt Gent
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Re: Shanty boat build - self design BBC materials

Post by Matt Gent »

For Suzuki and Tohatsu the 9.9 is shared with 15 and 20 blocks. May as well get the 20.

My 6hp kicker pushes the ~4000lb DE25 to hull speed in calm water, but that is for emergency use only. For long term I’d pick something with a larger prop, and better prop selection available.

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Re: Shanty boat build - self design BBC materials

Post by Jaysen »

As a person who is trying to get a program together to sail around the world in a 19' sailboat, you don't need to convince me that "bigger ISN'T better". The reality though is that you need to be able to get out of your own way in more conditions than just the current. The biggest factor for most displacement boats is wind. My guess is that you will find the 18hp more than enough for hull speed and HOPEFULLY oversized for winds up to about 20mph. My gut says that a modern 15hp propped down will get you what you want. If you can find a 9.9 two-stroke that is jet upgradeable to 15+ ... that's your sweet spot. Problem with those ugly turds is that they are noisy and messy.

Big things I would look for:
1. 2cyl motor: more torque for displacement hull
2. Larger prop shaft (standard with 2cyl) with a LARGE space between shaft and cav plate. This will let you prop up larger if needed.
3. remote throttle/steer and electric start. not all outboards have capacity for remote throttle and/or steering.
My already completed 'Lil Bit'. A Martens Goosen V12 set up to sail me to the fishing holes.
Currently working on making a Helms 24 our coastal cruiser.
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Re: Shanty boat build - self design BBC materials

Post by jbo_c »

silentneko wrote: Fri Aug 13, 2021 12:54 pm As far as 2ft bigger goes, I've never heard anyone say I should have built my boat smaller, lol. You never heard of 2ft-itis?
Absolutely nobody ever wishes a boat, barn, patio, or workshop was smaller. I tell people that all the time. :)

I’m just trying really hard to resist. I know from my past experience that the smaller and simpler it is, the more likely I am to use it more often.

If it weren’t for some “have-to’s” from my wife, this boat would be 18 feet, but making a boat she won’t enjoy enough to share with me regularly is a non-starter, so it has grown.

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Re: Shanty boat build - self design BBC materials

Post by jbo_c »

All good points, Jaysen. Thanks for the feedback.

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Re: Shanty boat build - self design BBC materials

Post by silentneko »

jbo_c wrote: Fri Aug 13, 2021 2:55 pm
silentneko wrote: Fri Aug 13, 2021 12:54 pm As far as 2ft bigger goes, I've never heard anyone say I should have built my boat smaller, lol. You never heard of 2ft-itis?
Absolutely nobody ever wishes a boat, barn, patio, or workshop was smaller. I tell people that all the time. :)

I’m just trying really hard to resist. I know from my past experience that the smaller and simpler it is, the more likely I am to use it more often.

If it weren’t for some “have-to’s” from my wife, this boat would be 18 feet, but making a boat she won’t enjoy enough to share with me regularly is a non-starter, so it has grown.

Jbo
I think you could fit what you want into a 20ft package, or even an 18, if you only ever intend for 2 people to be on board. That said the 18ft we rented had a tendency to wonder a bit as it was short and fat. An extra few feet of waterline would make it cruise better and more efficiently.

My plans are for 22ft, but with a euro transom for a generator. Instead of a 20ft with a swim platform/motor bracket. More waterline to increase speed and reduce draft.
Built: 15ft Skiff, 16ft Skiff, Modified Cheap Canoe, and an FS17.

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Re: Shanty boat build - self design BBC materials

Post by jbo_c »

What’s a euro-transom?

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Re: Shanty boat build - self design BBC materials

Post by jbo_c »

I’m all ears for ideas if you can fit it into 20’.

Must have:

Full time(not folding) full sized bed(in-line, not transverse)
Fully enclosed(no curtain) stand up head
4’ reclining area on deck
Stand up galley
Outside(front) helm
Room at transom to futz with motor if necessary
And, of course, room for stores and kit for several days

Admittedly, some of this incorporates my have-to’s as well. I can make it work in 22’ but can’t squeeze it into 20’ without compromising one of these.

Jbo

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Re: Shanty boat build - self design BBC materials

Post by Jaysen »

I keep coming back to the idea of a pontoon/tritoon platform. The biggest problem would be keeping the 'toons from being overloaded. That's when the barge seems better, but I think going with something that is a well-established, wide, and square platform would make your goal much easier.
My already completed 'Lil Bit'. A Martens Goosen V12 set up to sail me to the fishing holes.
Currently working on making a Helms 24 our coastal cruiser.
“Mark Twain/Samuel Clemens” wrote:Eat a live frog first thing in the morning and nothing worse will happen to you the rest of the day.
Jaysen wrote: Mon Apr 29, 2019 3:44 pm I tried to say something but God thought I was wrong and filled my mouth with saltwater. I kept my pie hole shut after that.

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