Designing & Building Hammerhead

Anyone care to share some advice on what anchor to go for? Sort, size, weight?

Hammerhead will be 35,000 kilograms at max load. And given her expedition use, we foresee lots of anchoring taking place.

Thanks!

Edwin & Veronika.

Salty Pelican said:

Anyone care to share some advice on what anchor to go for? Sort, size, weight?
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Rah Ro! Asking for anchor recommendations creates much Internet Angst and Debate!.

Over on Cruising Forum, there have been two very long, and very good, discussions about anchors. A couple, Noelex77 and SeaWorthyLass, at the time they were in the Med, started taking photos of anchors "set" by boats near them and posting on CF. This led to some interesting conversations. Panope started testing anchors back in 2015 and videoing how the anchors behaved. His discussion, which continues, is here, https://www.cruisersforum.com/forums/f118/videos-of-anchors-setting-155412.html.

His first post links to the discussion by Noelex77 and SeaWorthyLass.

It will take quite a bit of time to read all of the posts though.

If you are not a member of the Morgan's Cloud website, I would encourage you do join, it is an inexpensive membership and is a treasure trove of information. Though it is focused on sailboats there is much good information on the site, such as maintaining an aluminum boat and anchors.

The Morgan's Cloud anchoring "book" is here, https://www.morganscloud.com/category/anchoring-mooring/online-book-anchoring/ The Morgan's Cloud(John) discussion does mention/use some of the tests done by Panope that was linked up thread, but John has his own opinions based on living on a boat.

The Dashews books are available for free, https://setsail.com/free-books/. While some of the information is dated, and their anchor advice might have evolved since the books were written, it is still good information.

I believe that Dashew and Morgan's Cloud recommend looking at a given brand's size chart and then getting the next larger size, or two, from what the chart indicates.

John at Morgan's Cloud provides an answer to your question of which anchor, https://www.morganscloud.com/2019/04/09/spade-sarca-excel-or-some-other-anchor/ His answer is Spade but one should read why that is his answer.

Later,
Dan

John is big on a spade and against any with a roll bar. We used a Rocna for 8 years and it was excellent in any thing but loose mud. Know he says they don’t reset well but for us that never occurred.
Think you need to consider your ground tackle set up and your most likely cruising grounds. Are you going to deal with a lot of wind shifts, loose mud, shell beds, thick weed or other hindrances. Don’t think any anchor does everything well. Rather some are better than others in a given circumstance. Looking at your build would think a spade with a danforth secondary might be a decent choice.

Spending our holidays at Lake Balaton has slightly changed our boat plans.

Regards, Edwin & Veronika

Salty Pelican said:

Spending our holidays at Lake Balaton has slightly changed our boat plans.



Regards, Edwin & Veronika

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But still the same long, narrow hull form, Bimini, and expansive views [emoji3]

I'm sure that's still self-righting up to the same angle of heel as your prior concept. Right?

But what kind of anchor does it use?





Later,
Dan

Haha, you guys are too funny! Today we had an introduction to the noble art of riding an electric surfboard. Mighty much fun!

Regards, Edwin & Veronika.

And another pic!

Salty Pelican said:

And another pic!

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Uhhh, I think you're supposed to stand up on those things!

Yeah ... and I was so proud to just be able to sit on one!

Regards, Edwin.

Having completed the concept design phase (and having ticked all of the boxes), we are now moving forward with the detailed designs of the Hammerhead Yacht. Very exciting times! We have gotten a lot of feedback, via this forum and other sources. There's even interest from other boaters that find the project to their liking. We'll keep you posted of our progress!

Regards, Edwin & Veronika.

Looks good!



Later,
Dan

Salty, looking at your latest concept render above, I'd suggest not installing a modern anchor, otherwise you'll end up with the ugly battering ram like the Dashew series and so many other plumb bow boats.

I'd suggest a stockless, nestled up on your bowplates in a anchor hawse hole. Install a HHP anchor of extra-very heavy weight and you'll be good in pretty much any bottom type on earth.

One of the best all-around is the Poole, although personally I prefer an AC-14 because it is better in rocks (everything is good in sand!). There are also some SHHP stockless, but those aren't as good in all-around conditions (they are mostly focused on sand/mud).

Thanks for sharing, Mako and Dan!

Here's a graph I'd like to share on engine power requirements for the Hammerhead. At minimal, medium, and heavy load conditions.

Regards, Edwin.

50 shp at 9.0knots is extremely low. That’s obviously smooth water calculation, but even if you require 70-80hp with wind and waves, that’s still really economical

Regarding anchor placement.

I like what Dennis is doing on his larger LRC designs. He is offsetting the anchor to one side, port usually, which keeps the LOA down but also opens up the bow so it could be used as a way to get on/off the boat.

Later,
Dan

How IS the anchor planned to fit/work?

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.

Salty Pelican said:

Thanks for sharing, Mako and Dan!

Here's a graph I'd like to share on engine power requirements for the Hammerhead. At minimal, medium, and heavy load conditions.

Regards, Edwin.

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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.

sean9c said:

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.

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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.

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.

Mako said:

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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I agree.

Regards, Edwin.

twistedtree said:

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.

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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.

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.

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.

Mako said:

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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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

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.

Sailor of Fortune said:

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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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.

Scenic pics of our last little boat trip! Yeah, well, it was misty ...

Regards, Edwin & Veronika