The Difference Between an Inshore and Offshore Boat. Would you take a Boat l...

[neilpride]

Originally Posted by Cavalier

Right. I have answers! - not all the answers, but some of them...

Below is how the Keel is assembled on the Oceanis range (i doubt it varies too much with the First range). On my 461, PMS60 wasn't used, but 3M 5400 (beige in color) was. My bolts were apparent SS (but the grade hasn't been specified). The heads come from the factory unpainted, but PO must have coated mine with bilgekote as that's how they now look. I'm going to wire-brush the paint off a couple of them during the next week and post what I find.

Another thing to note is that even-though the keel is cast iron (and epoxy encapsulated), is isn't threaded directly. Threaded inserts are [apparently] bonded into the keel mold during forging, such that they are an integral part of the keel, but not the same material.

Preparation:
- Grind out the hull bottom where the keel is to be bonded: sand down the gel coat
superficially and scratch the area.
- Dust off and degrease the area with MEC (Methylethycetone MEC).
- Mask the keel profile around the edges of the keel sole with adhesive tape.
- Degrease the keel sole surface with MEC.
- Apply PMS 60 glue all around the edges of the keel sole bilge recess.
- Apply PMS 60 glue on the whole surface of the keel sole.
- Spread out the PMS 60 to get a regular thickness of the glue by 2mm.
- Apply a seal of glue around the inserts or threads.

Assembly:
- Fit the two guides (threaded rods) into the two front and aft axial inserts n° 1 and 2 of the keel (schematic 1).
- Move the keel to come close to the hull bottoms, guided by the threaded rods.
- Apply PU 501 glue on each bolt (underneath the washer) on a height equivalent to the thickness of the hull plus one time the diameter of the bolt.
- Position the bolts and washers or metal plates from the center to the ends (screw by hand on a few turns). NOTE: plates and washers must rest on a flat surface.
- Control keel alignment compared with hull axle.
- Tighten the bolts progressively and regularly, starting from the two front and aft bolts, then alternate 2 by 2 (follow the numerical order as described below). (Do not exceed more than 3 or 4 turns).
- Tighten the bolts a second time, with the dynamometric spanner according to the following numerical order (described below).

The Bolt arrangement has 8 bolts, a forward, and aft and 3 pairs mid-keel. The recommended tightening order is the same as for a standard flange. Once that's been done, the order pattern is rotated 90degrees such that you start the torqueing on a different bolt but maintain the pattern.

{the below tables may not render correctly - apologies if so}

TABLE N°1: STEEL BOLTS AND NUTS QUALITY 8-8.

DIAMETER

M14

M20

M24

M30

QUALITY

8-8

8-8

8-8

8-8

TORQUEMAXI(N.m)

88

265

451

882

TORQUEMAXI(m.kg)

9

27

46

90

TORQUEMINI(N.m)

49

127

225

441

TORQUEMINI(m.kg)

5

13

23

45

TABLE N°2: SS BOLTS AND NUTS.

DIAMETER
M14
M20
M24
M30
M36
M42
TORQUEMAXI(N.m)
108
314
539
373
637
1020
TORQUEMAXI(m.kg)

11

32

55

38

65

104







TORQUEMINI(N.m)

49

157
274
186
323
510
TORQUEMINI (m.kg)

5

16

28

19

33

52

Cleaning:
- Clean glue excess around the bolts heads and washers with MEC.
- Clean oustide keel/hull junction seal and remove the masking tape.
- Clean and degrease the keel/hull junction with MEC.
- Apply a seal of PMS 60 glue at keel/hull junction: Smooth the seal by the finger, press hard to make sure no air void appears when drying.

The tops of the bolts (i.e. top of the thread) is also bonded to the ID of the hole through the hull with PMS60, to help ensure that

When it comes to how-often one should torque the bolts, I was advised 'off the record' (i.e. not the written record) that as long as there was no evidence of gapping in the region of the keel/hull bond, no signs of corrosion near or around the bolts in the hull, nor unexplained water intrusion into the bilge - then it'd be smarter not to touch them! (makes sense).

Wow good info, thanks for that!! .

[Terra Nova]

The bolt heads are usually marked with the material.

[Cavalier]

Originally Posted by Terra Nova

The bolt heads are usually marked with the material.

Exactly. My guess is that they're going to be A2. I doubt A4 (which'd be much much better), as that'd be too good!
Of course, the 18-8 only refers to the Chromium Nickel % in the alloy, but doesn't specify the other sub-alloys required for 300 series alloys.

[neilpride]

Why not Nitronic 50? as far in know in the rod rigging bussines the alloy is superior to any SS in corrosion and strength resistance.

[Cavalier]

Originally Posted by neilpride

Why not Nitronic 50? as far in know in the rod rigging bussines the alloy is superior to any SS in corrosion and strength resistance.

That's a useful little diagram!

[hellosailor]

"Apply PU 501 glue on each bolt "
Sounds like re-torqueing would be unfeasible, since the nuts have been glued onto the bolts. You'd have to remove the nuts and washers, clean the bolt threads, and reglue during retorquing. No?

Cast iron is also rather brittle, so putting threaded inserts into the keel casting, instead of trying to tap them into cast iron itself, sounds like a very logical way to do this kind of keel.

[poiu]

Originally Posted by neilpride

Why not Nitronic 50? as far in know in the rod rigging bussines the alloy is superior to any SS in corrosion and strength resistance.

True nothing else offered currently for rigging, but Nitronic 50 is not superior to any SS at all. There are many superior alloys. Nitronic 50 was developed in the late 1960s and much water has flowed under the bridge since then. If looking at PREN as a crude and inadequate comparison measure. Nitronic has a PREN of 38. Better than 316 having 25 and 304, which has 19. The better stainless alloys might include 654 SMO with a PREN of 54 or AL 29-4 at 44. Many other grades with much lower PREN numbers are superior to Nitronic in research papers for crevice corrosion. The fact that there are no others used in rod rigging doesn't mean it is the best. There are many reasons why there is no superior material offered including the large profits to be made from frequent change-outs required.

For bolts a better choice is: bronze, inconel and titanium.

[boatman61]

Seeing as this has gone all technically speak and statistics and numbers.. I've decided to join in ..
The difference is.. The size of the owners nuts..

[neilpride]

Originally Posted by poiu

True nothing else offered currently for rigging, but Nitronic 50 is not superior to any SS at all. There are many superior alloys. Nitronic 50 was developed in the late 1960s and much water has flowed under the bridge since then. If looking at PREN as a crude and inadequate comparison measure. Nitronic has a PREN of 38. Better than 316 having 25 and 304, which has 19. The better stainless alloys might include 654 SMO with a PREN of 54 or AL 29-4 at 44. Many other grades with much lower PREN numbers are superior to Nitronic in research papers for crevice corrosion. The fact that there are no others used in rod rigging doesn't mean it is the best. There are many reasons why there is no superior material offered including the large profits to be made from frequent change-outs required.

For bolts a better choice is: bronze, inconel and titanium.

Quite right, but as i say , in the rigging bussines..... rod have a infinite life span without the cold heads, i mean the problem its in the ends, Bronze not sure for keel bolts, maybe yeah as marskeel offer the option with Nitronic and aqualoy 22 and 2205 duplex alloys .

[sailorboy1]

Originally Posted by boatman61

Seeing as this has gone all technically speak and statistics and numbers.. I've decided to join in ..
The difference is.. The size of the owners nuts..

Nut size only matters if stub size matches!

[hellosailor]

Rod companies might not all be fools or thieves. Without kidnapping an engineer to be sure...the rod alloy might still be superior when it comes to reforming those ends. Or, to how it wears against the fittings, as opposed to using another alloy. Or some other obscure point of long term metal-on-metal that isn't obvious. Maybe it is just better at recovering after being coiled up for shipping and storage.

[Cavalier]

Originally Posted by sailorboy1

Nut size only matters if stub size matches!

..and whether it's full thread or not!

[poiu]

Originally Posted by neilpride

Quite right, but as i say , in the rigging bussines..... rod have a infinite life span without the cold heads, i mean the problem its in the ends, Bronze not sure for keel bolts, maybe yeah as marskeel offer the option with Nitronic and aqualoy 22 and 2205 duplex alloys .

I hope I am not mixed up about what you and Boatie are saying. Large nuts, cold heads and rod ends - all lead to an infinite life? Maybe the route to eternal bliss.

[hpeer]

Not no steel boat owners are partaking of this conversation!

No nuts or bolts, the keel is integral to the hull.

Just saying!

[Jbingham]

Originally Posted by hpeer

Not no steel boat owners are partaking of this conversation!



No nuts or bolts, the keel is integral to the hull.



Just saying!

Can't be safer that's for sure!! And a very relevant point to my original question. It wasn't can a boat like CR make it on a journey offshore especially with the RIGHT crew and weather. But when situation turn dire, and the conditions deteriorate having a boat made for blue water vs coastal cruising and racing I would have thought an easy discussion. There has subsequently been some great points that if you do take a boat not designed for the open ocean offshore, be sure to understand how far you can push her. And in advance, keel aside I'd want to know every enhancement structurally to make to ensure the safety of the crew and the vessel herself.

Plan for the worst!