Paravanes boom position?

Cold-smoked said:

Thanks Jim, those plans and pic look great - and I'm certain that your paravanes will work very well with the poles being in that position. Will you dare to climb up to the lookout while at sea ? The nest sure looks cool

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We will see. When standing in the crows nest your head will be 20' off the deck and 32' off the water! I think we will start with climbing to the nest at the dock. We will have a harness system in place for the ladder and the crows nest. Of course, for your YouTube channel we wil have to install a gopro up there permanantly!

I will be looking forward to how your paravanes perform once completed.

Jim
M/V Sea Venture

Thanks, and that's pretty high up ! A Gopro is a great idea !

Just to help motivate your climbing up there, here's a pic of the very last Norwegian seal-hunt vessel. They used to hunt seals near Greenland, their nest is also tall and windy Harness is a very good idea, btw.

Their last trip (2015) was recently aired on TV, btw - that's why I came to think of it.

Cold-smoked, how did you notch your pipe? Band saw?

Xsbank said:

Cold-smoked, how did you notch your pipe? Band saw?

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Hi, I use a 5" angle grinder w/variable speed for all the cutting, grinding and sanding.

Just playing some more with the overall appearance. This would surely raise eyebrows up here :lol:

Cruising Sea Venture said:

Of course, for your YouTube channel we wil have to install a gopro up there permanantly!

Jim
M/V Sea Venture

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I actually thought about this myself a while back, to have a camera high up in the mast with a live feed to a monitor inside the wheelhouse. Our wheelhouse is far aft, so a camera would be great to help see the bow. I guess we would need a tiny wiper/washer for that. I will look into it.

Thank you Cold!

CS: The guy who did the final design/installation for our paravanes, did a mock up with pvc pipe first. He said he did that for every Installation.

Larry M said:

CS: The guy who did the final design/installation for our paravanes, did a mock up with pvc pipe first. He said he did that for every Installation.

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Yes, that's a good idea. I thought about using 2x2 fir myself, just to play with the shape of it - but I think maybe my drawings will do. I am playing with drawings, actual measurements and photos of the boat from different angles. One of the obvious criteria we have is that we shouldn't bump our heads into the frames when walking past the wheelhouse. One other thing is that the frames and poles (while at rest)must point slighty inward, to avoid damage to them if the boat rolls while being moored next to our quay. The difference between high and low tide here is usually around 2 meters, and 3 meters maximum.

Today I cut the poles down to 17 feet, drilled the bolt holes and welded on end caps. Even though it's cold, it's great to work a bit outdoors in nice, crisp and sunny weather. This is the 6th or 7th straight week of lovely dry weather

Vanes

Vanes are mostly done, I had to buy one 8 ft x 3 ft sheet of ply - so there's plenty left for spares. I will give all the parts 2-3 coats of epoxy now before I assemble. As lead is hard to find here, and melting old batteries is too much of a hassle - I think I will try these 10 kg/~25 lbs weight lifting plates. Any better ideas ? I think it may work well, but I sure would prefer to have lead. Vanes are close to 300 sq inches, btw.

Can you find a small trolling cannon ball and cut it in half? Google “commercial trolling cannon ball”. Does the Norwegian commercial fishing industry have such things available?the sport fishing stuff is too small.

JDCAVE said:

Can you find a small trolling cannon ball and cut it in half? Google “commercial trolling cannon ball”. Does the Norwegian commercial fishing industry have such things available?the sport fishing stuff is too small.

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Thanks, but I did look around here for that. It seems the pros here don't use lead much.

So you may have to make them yourself. I would really consider the lead half sphere as it is more compact and is more resistant to corrosion. Here is the weight of cannon balls of different diameters.

Volume of a sphere: 4/3*pi*radius^3 (cubed)
4/3*pi=4/3*22/7=4.190, constant for all calculations.
Weight of cubic cm of lead is 11.34 g or 0.01134 kg

Here are my calculations for half spheres of lead of differing radii:

JDCAVE said:

So you may have to make them yourself. I would really consider the lead half sphere as it is more compact and is more resistant to corrosion. Here is the weight of cannon balls of different diameters.

Volume of a sphere: 4/3*pi*radius^3 (cubed)
4/3*pi=4/3*22/7=4.190, constant for all calculations.
Weight of cubic cm of lead is 11.34 g or 0.01134 kg

Here are my calculations for half spheres of lead of differing radii:

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Thanks, I will think about it. I melted some lead (~8-10 kgs) last year from a bunch of wheel weights, to use as ballast in a RC trawler that I made. So I may just have to do that again. But in case I lose one or both vanes, it would be great to use something which is easy to find here.

Errata: The 5th column is mislabeled. Here is the corrected table.

Cold-smoked said:

Thanks, I will think about it. I melted some lead (~8-10 kgs) last year from a bunch of wheel weights, to use as ballast in a RC trawler that I made. So I may just have to do that again. But in case I lose one or both vanes, it would be great to use something which is easy to find here.

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Chuckle! I understand they are still "extracting" stuff from the Tirpitz. I'm sure there's more than enough lead in that keel! That's close to where you are!

JDCAVE said:

Chuckle! I understand they are still "extracting" stuff from the Tirpitz. I'm sure there's more than enough lead in that keel! That's close to where you are!

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Haha, I said EASY to find !

But you are correct, the remnants of the Tirpitz are very close to where I live.

My fish are made of galvanised steel and the main weight is a steel bar (also galvanised).

This picture was taken when I first got the boat and had not installed the lifting tackle yet. The steel bar sits in that circular piece of aluminum which holds the fish very securely.

Xsbank said:

My fish are made of galvanised steel and the main weight is a steel bar (also galvanised).

This picture was taken when I first got the boat and had not installed the lifting tackle yet. The steel bar sits in that circular piece of aluminum which holds the fish very securely.

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Thanks, Xsbank. Your vanes look big, how much do they each weigh ? For my wooden hull I think it's wise to use softer materials, and I've rounded off all the edges a little. I just put on two coats of epoxy to the ply, curious to see if it will last. HDPE is probably a good alternative to ply.

Actually, I have never weighed my fish but judging by how long after that I suffer, I would bet 30-35 kg.

Xsbank said:

Actually, I have never weighed my fish but judging by how long after that I suffer, I would bet 30-35 kg.

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Wow, a lot to pull up over the railing by hand. With a 10 kg nose weight mine will weigh around 15 kg each. Maybe that's too light then, I will see.

I think the idea is to keep them under the water hydrodynamically, not by weight alone. As long as yours don't actually float you should be fine.

Xsbank said:

I think the idea is to keep them under the water hydrodynamically, not by weight alone. As long as yours don't actually float you should be fine.

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Yes, I'm sure the actual angle of attack matters more than weight - at least while under way. At stop or very slow speeds it might be different.

Your vanes look similar to these Kolstrands, their 300 sq in weighs around 5-6 kgs more than mine will. Yours could be the next size up then, for 60-70 ft vessels.

We have 3 positions we can run the fish, We use the middle. I was told that the most forward was for 12-15 knots and the rear was about 3-5 knots. We run at 6-7 knots. These are about 300 "sq and the lead weight is 27lbs. The top picture of the fish has what is called a "kelp cutter". The new fish I just put on Hobo, I don't have them.

Larry M said:

We have 3 positions we can run the fish, We use the middle. I was told that the most forward was for 12-15 knots and the rear was about 3-5 knots. We run at 6-7 knots. These are about 300 "sq and the lead weight is 27lbs. The top picture of the fish has what is called a "kelp cutter". The new fish I just put on Hobo, I don't have them.

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Thanks, and that makes sense.

Guys, guys

I know most if not all of you with paravanes have fore guys and aft guys and so on. I will probably use steel cable or amsteel equiv. myself for fore guys. Solely because of discreet appearance.

But I'm thinking if I really need a dedicated aft guy ? What if I instead offset the top cables' hub/bracket at the mast just slightly ? As the poles will be in front of the A-mast, the connecting hubs could simply be from mast centre to pole centre. There should be a fairly low, but constant pulling force toward the stern because of this slight difference in angle. That is in addition to the pull from the vanes. Could this be enough, or is this pulling force to weak, uneven and erratic ? I know the safest is to have lots of guys, and I guess I will have to test this using a crane weight or/and experience it first hand.

Just thinking out loud, wish to keep it simple - with as few parts as possible

This is a simple and exaggerated top/birds view sketch of my boat : blue line is the top cable.

It could work but I would be concerned that during retrieval and deployment of the poles, in any type of sea state, that the pole could rotate or move forward or aft or you would have minimal control at the mounting bracket for the pole at the hull.

We have no aft guy but a piece of 1.25" aluminum forward at ~45 degrees to keep the pole from rotating and to keep it perpendicular to the hull during retrieval and deployment.

The second picture shows some detail of the A frame and pole attachment at the hull (before we repainted).

If you need any detail, I'd be glad to take some specific pictures or measurements. It would have to tomorrow though, as were moving the day after and I'll loose the good internet.

Thank you, Larry. I see your point, and you are very helpful. I appreciate it.

Hello Cold, definitely guys both ways, think of the stresses if you are turning across waves and you get some corkscrew motion, or following seas...?