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Old 09-07-2021, 08:22 PM   #141
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Originally Posted by sean9c View Post
I'd think that with a generally light weight and a narrow bow you'd be concerned about weight in the bow and that might lead you to an anchor with more holding power per pound than a stockless.
Honestly I think that this often-heard concern is overstated. Let's give an example, say the recommended Rocna is a 100lbs. An equivalent HHP stockless would need to be 150lbs, although I'd recommend a 200lb stockless since ground tackle is so critical. So the additional weight is 100lbs. Big deal. That's the weight of a teenage girl standing on the bow. Do you think that a teenager standing on the bow will result in porpoising and dangerous plunging into head seas? No way.

However, as we've learned on countless threads, anchor choice is personal and quite contentious.
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Old 09-08-2021, 01:02 AM   #142
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Thank you all for chiming in and sharing your thoughts, opinions, and experiences. Much appreciated! I will try to dive into your posts and see if I can give more info where needed. It is still early morning here, and I am on my first cup of coffee, so if I forget someone or some question, please be gentle.

On anker choice ... we haven't decided yet. I don't like the "out over the enter line of the bow" design, since it makes the ship longer. I don't like the over one side or the other approach much either. I think it is esthetically less pleasing. Anker to the side, against a plate ... not sure. This ship will travel through the waves, not bounce over them.

We are currently thinking of placing the anker on dek on a designated place/fitting/mold (hope that makes sense) and have a spring loaded beam carry it forward, once we want to use the anker. We discussed having two ankers. Since each variety seems to come with strength and weaknesses. So - depending on the bottom we are ankering into - we can attach the appropriate piece of equipment.

Any suggestions as to what combination would be best?

Thanks!

Edwin & Veronika.
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Old 09-08-2021, 01:06 AM   #143
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Quote:
Originally Posted by Mako View Post
Honestly I think that this often-heard concern is overstated. Let's give an example, say the recommended Rocna is a 100lbs. An equivalent HHP stockless would need to be 150lbs, although I'd recommend a 200lb stockless since ground tackle is so critical. So the additional weight is 100lbs. Big deal. That's the weight of a teenage girl standing on the bow. Do you think that a teenager standing on the bow will result in porpoising and dangerous plunging into head seas? No way.

However, as we've learned on countless threads, anchor choice is personal and quite contentious.
I agree.

Regards, Edwin.
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Old 09-08-2021, 01:38 AM   #144
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Originally Posted by twistedtree View Post
It's really interesting to see the physics of boats playing out here, in particular with respect to displacement and a long/skinny shape.


In rough numbers, you require 100 hp to make 35 tons go 10 kts. My similar length boat is 3x the displacement which would suggest 3x the HP, or 300 HP. But I take 400 HP to go 10 kts, the difference I expect caused by my much wider beam.
Hi TwistedTree,

What I learned is that, yes, total volume of the under water hull (and associated displacement weight) is very important. So a ship that displaces 3 times more water should (-ish) consume 3x the amount of fuel. I think I can explain your 4x though.

Diesel consumption is not just about displacement. It is also about under water hull lines. Imagine the Hammerhead being optimized for 10 knots cruising speed. This means that the angles of the under water ship - as it sails through the water - need to be at certain degrees. Since my ship is less wide and sits less deep in the water, given the same Length Over Water, Hammerhead's angles will be lower compared to yours. Let's say ours are 7 degrees max and yours are (just as an example) 10 degrees. The 7 degrees correlates with a speed of 10 knots. Resulting in Hammerhead maintaining good contact with the water it travels through at that speed. The speed it is optimized for.

Now, in a boat with the same length, but a deeper under water body, by definition the angles will be higher. Hence the 10 degrees example. Now, I don't have all the numbers readily available, but it is easy to imagine a ship with those higher angles of attack, traveling at 10 knots will loose contact with that water. The water wants to part from the hull and travel in a more straight line. This results in vortexes, low pressure fronts under/behind the boat, high pressure front nearer to the bow, generating lift, further deteriorating the angle of attack, and an overall larger actual displacement of water.

The way I look at it, is that a ship optimized for a certain speed, will have an actual real-life water displacement as close as possible to the passive displacement weight. The further any boat deviates from its optimal speed, the more water (more than the passive displacement weight) is moved, resulting in lower overall efficiencies. Stern and bow waves, created by a boat at higher speeds are water that is displaced. An amount above the water place the ship takes up at rest. To move this additional water, costs energy.

I think this explains the 33% additional loss in efficiency that you get at 10 knots. It might also mean that your boat is optimized for - say - a speed of 8 knots and that at that speed you do get the 3x number?

Regards, Edwin.
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Old 09-08-2021, 03:40 AM   #145
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I think bow and stern waves are a good indication of the amount of disturbance created by sailing above the optimal speed a hull is designed for.

Regards, Edwin.
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Old 09-09-2021, 03:02 PM   #146
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Range!

Here are the range calculations at various speeds. They include 24 kWh of additional electrical power produced by the generator on a daily basis. That's - given the advanced solar panels that will be added and the batteries on board- not really needed, but I think being a bit more conservative always is a good starting point.

The numbers are based on an 80% use of total fuel. In other words, there is a 20% reserve, just to be sure. Stabilizer fin resistance and operation is also factured in.

Regards, Edwin & Veronika.
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Old 09-09-2021, 04:13 PM   #147
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Originally Posted by Mako View Post
Honestly I think that this often-heard concern is overstated. Let's give an example, say the recommended Rocna is a 100lbs. An equivalent HHP stockless would need to be 150lbs, although I'd recommend a 200lb stockless since ground tackle is so critical. So the additional weight is 100lbs. Big deal. That's the weight of a teenage girl standing on the bow. Do you think that a teenager standing on the bow will result in porpoising and dangerous plunging into head seas? No way.

However, as we've learned on countless threads, anchor choice is personal and quite contentious.
as we all know, ground tackle weight is a lot more than just the weight of the anchor. Chain weight adds a bunch more "little girls" weight forward
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Old 09-09-2021, 08:15 PM   #148
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I think Dashew's approach is interesting, the largest hi performance anchor that you can stomach and then hi tensile chain in order to get smaller link, lighter chain.

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as we all know, ground tackle weight is a lot more than just the weight of the anchor. Chain weight adds a bunch more "little girls" weight forward
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Old 09-13-2021, 01:54 PM   #149
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Update on our boating adventures and more ...

Very exciting times! The mss. and I are just back from a three day boat trip to Zaltbommel and Heusden. Both with beautiful almost medieval city centers. We enjoyed the trips. Six hours on Saturday, from Vianen to Zaltbommel. Just a short, three hour hop from Zaltbommel to Heusden. And today the last leg: From Heusden back to Vianen via some beautiful scenic landscapes.

We enjoyed the boat, the weather, and tried the local beers & food. Here are a few pics!

Before the weekend we commissioned phase 2 and 3 with our naval architect. The basic as well as detailed design plans for our new boat! We also visited some shipyards together and are working on the request for quotations as we speak. The project is moving along nicely!

Regards, Edwin & Veronika.
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Old 09-14-2021, 03:57 AM   #150
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Scenic pics of our last little boat trip! Yeah, well, it was misty ...

Regards, Edwin & Veronika
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Old 09-14-2021, 04:37 PM   #151
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Scenic pics of our last little boat trip! Yeah, well, it was misty ...

Regards, Edwin & Veronika

Misty Be Good.


Well, it is pretty while the boat is not moving. Not so pretty when the boat is moving.


Later,
Dan
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Old 09-14-2021, 05:02 PM   #152
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Dan, I loved getting to the water early! Sounds are very clear in misty conditions. AIS was an amazing help. Sailing slowly, like 5 knots ... totally enjoyable!

Regards, Edwin.
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Old 09-17-2021, 02:09 PM   #153
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Here are two pictures of the ventilation plan. Our boat will have heating as well as airconditioning. Since she's an ocean-going boat, with roll-over / self-righting capability, we want the boat as air-tight as possible. Air-tight = water-tight. But that means we need forced fresh air ventilation. Anyhow, enjoy the pics!

Regards, Edwin & Veronika.
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Old 09-20-2021, 02:51 AM   #154
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Safeguard rails or not?

In the picture underneath, you see a sailboat with a safeguard rail situated above the windows. Sailors can connect their harnas to it and safely move up and down the boat. Now, we are designing a motor yacht, with stabilization, and - of course - no sails that need to be managed ... but would this still be a good addition, given the expedition-style cruises we anticipate? Higher latitudes, bigger waves? What say you?

Regards, Edwin & Veronika.
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Old 09-20-2021, 05:51 AM   #155
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In the picture underneath, you see a sailboat with a safeguard rail situated above the windows.

Salty, thatís just a handrail. On sailboats we ran a wire, only attached at the ends, so our harness would slide without having to be removed and re-attached continuously. All the short stantions in the photo actually increase the hazard for that purpose.

Having said that I think itís a 100% solid idea to have handrails on both side of your side decks, donít just rely on one side in heavy seas. In big seas I would actually crouch down even though I did have both sides, trying to get my COG below the top of my horrible 30Ē high railing.

BTW, follow commercial specs (CE, ABS, etc.) and go with the 1 meter high railing.
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Old 09-20-2021, 06:04 AM   #156
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Thanks for chiming in, Mako. As I understand it, it is not a handrail, but one connects a little "cart" to it, that allows the sailor to walk forward and back, while being attached. The construction can take 2000 kilo's or 4,400 pounds. I'll see if I can find another picture that explains it better.

Yes, railing will be 1 meter high!

Regards, Edwin.
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Old 09-20-2021, 08:38 AM   #157
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It would be interesting to see what your traveler looks like - it is something that is repurposed from a sailboat?
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Old 09-20-2021, 09:16 AM   #158
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If we'll add it, it will be proven technology, as used on aluminium expedition sail boats, Mako.

Regards, Edwin.
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Old 09-21-2021, 04:32 AM   #159
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We are thinking to equip the boat with a 55 kilo Rocna anker. With 100 meters of chain.

Regards, Edwin & Veronika.
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Old 09-21-2021, 07:22 AM   #160
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Had a Rocna and loved it but for the next go round will switch to a Spade. Didn’t like reset with 180 current or wind shifts and loose mud performance. You’re building an amazing boat. Expect you’re going to be a world traveler so will experience many types of bottoms and also 180 shifts in places. Become convinced all the roll bar anchors have issues in those settings. Think weighed tips really help in packed sand, weed and grass. Used the Rocna at 3:1 and didn’t drag even in fresh breezes. It’s an amazing anchor but think for an all situations anchor the Spade is better.
P.S. - would still carry a fortress as a secondary regardless of what you choose as a primary. Think nothing does better in loose mud.
I’m with you on the 100m of chain. Know on another thread folks were saying 200’ suffices. That’s true until it doesn’t. If you cruise enough those situations definitely come up.
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