Adding Lead To Keel,

[col blumson]

I have about half a ton of lead just sitting under the floor and should be tried in at least.
But the boat 1980 IOR ex racing yacht, is a bit tender thus it should be at the bottom of the keel. I propose to drill through the bottom of the keel put SS rods through protruding so that I can cast the lead around the base of the keel, I would mould the base to be round and shaped as a bulb but flat on the top. Thus some what a fined keel.
Any one with some thoughts would be great to hear.
thanks silly old Col

[delmarrey]

A few years ago I considered the doing the same to my 40' IOR. But two things one has to consider. Can the keel bolts take the extra stress on a close haul, and can the standing rigging take the extra weight?

I'm sure my bolts and rig can take it but I've already had to raise my boot stripe 5" just to compensate for all the off-shore equipment and gear. Adding more weight to the keel starts changing the dynamics of the hull design.

[Stumble]

Col,

It is absolutely doable, but it isn't easy or cheap. From a financial standpoint it is probably less expensive to just replace the boat.

As Del mentioned the added weight adds extra stress to the keel bolts so the entire keel grid attachment needs to be reverse engineered to ensure it is strong enough to handle all the extra loads. Just a rough guess is that you have a 6' keel? So this is an extra 6,000ft/lbs of torque that needs to be accounted for. Depending on the design of the boat this may be close to 50% of the entire current design. And since it's an IOR design there is good reason to believe that very little extra strength was built in.

Again this extra RM also changes the rig design. The mast can probably take it (rigging is usually designed around a safety factor of 3), but you would be eating up a lot of that safety factor immediately. I guess you could put in a new stick, replace the standing rigging, and then re-engineer the bulkheads to carry the loads...


All in all it would be a massive project, and I can't help but think why?

[Snowpetrel]

Pretty common in racing circles to play around like this, normally new keels and the like... look at what the mexicans are doing with the old ior warhorses. Big deep "t" keels and turbocharged rigs. I have also seen pics of an old ior beastie up in the PNW with a serious bulb.

The standard ior has a pretty solid keel, with a much bigger foot print than most modern designs so it may not need additional structure to deal with the extra loads. Best to run it past a NA (naval architect) to be certain. The rig loads will go up, but probably not much more than with 8 guys sitting on the rail so again a NA might be happy with the calcs depending on the rig.

Be aware that the bulb doesnt always add speed overall all the time. The extra drag slows the boat, anytime she cant use the extra stability. And the extra pitching moment can slow the boat in light air with a swell.

Mars keels have some interesting links and so does Eric Sponburg.

Interested to see what you come up with, having an old Ior warhorse myself.

Sent from my GT-P5210 using Cruisers Sailing Forum mobile app

[jannw]

yes, people do it ... professionally see marskeel ... and you can probably figure out how to DIY from them Keel Draft Reductions | MarsKeel

[denverd0n]

A boat is not like a chinese menu... One from column A, one from column B, mix and match however you like. It is a system, where everything works together. Change one thing and it affects everything else. Do you fully understand what all of those other effects will be?

If you're not a qualified naval architect, who understands all of the interactions involved in yacht design and can work out all of the engineering formulas, then this kind of a dramatic change is a complete crapshoot. Maybe it will work out great, or maybe it will be a disaster. Possibly even a seriously dangerous disaster.

Do you really want to take that chance? Your choice, of course. Personally, I would just sell the boat and buy one that was actually designed to function the way that I want it to, rather than trying to redesign and rebuild a boat that is fundamentally unsuitable to my needs to begin with.

[lifeofreilly57]

Some earlier IOR boats went this way, my old boat had a custom keel by naval architect Chance, (cant remember his first name). It actually did enhance the boats sailing ability but of course there's always a trade off.
It was deeper and different in shape, with some added ballast under the floor boards secured with some additional bracing.
Remember though that IOR designs were intended to heel to gain waterline length, that boat didn't really start to get near hull speed without getting to 15-17deg of heel, and it would still heel more as waterline increased.
It was a monster upwind, even more so with the mods, but sometimes needed crew on the low side when on a beam reach to get it to to heel enough to get more waterline length and speed potential.
It also didn't help downwind performance at all, in fact I feel it made it a bit more squirrely downwind, of course it's all relative since I was usually sailing at it's the limit in those cases.
Adding a bulb was also a popular solution on some of those boats but I'm not sure it's a universal solution, keel bolts are usually oversized for their application but that's totally dependent on the model and maker. As stated before, it also adds drag, but shape and size also come into play.
How do you define "tender"? In an IOR boat they're meant to heel to a certain degree and then tend to take a set like they're on rails, at least the ones I've sailed on did. In a puff they heel, then accelerate and settle into a groove, in that transition they tend to feel unsettled but actually just keeping a steady hand moves through that transition. It might seem a bit extreme to someone coming from a cruising design but anyone who owned some from that era has no problem with the dynamics of those designs. Unless of course you own one that was built to the extreme end of the spectrum, like all design criteria some designers tend to go to the limit of any rule and there were some real stinkers from that set of rules.
Trying to make the boat too stiff will negate an benefit gained from the original design, it will never be as stiff as a cruising design and trying to do so will just make it slower and less responsive.
If you want to add a bulb, by all means do so, but run it by a naval architect first, or at least one of the companies that do keel modifications, if they've had any previous experience with your particular model they might just have a solution for you. You want to have an actual benefit for the time and expense of doing this, you don't want to degrade the boats sailing performance.

[TxMarineRepair]

I would like to suggest a completely different approach. Since the only stated reason for your proposed change is to add stability, why not just reduce the heeling forces. (Full disclosure - I am a sailmaker as well as an owner of an old IOR boat that is tender too). If I were in your shoes, I would:
1. Remove all the loose lead from the bilge and sell if for scrap. At about $.50 per pound you get $500. The boat will be lighter (and in theory faster on most points of sail) or at least you will have compensated for 1000# of cruising gear you have put aboard.
2. Then I would look into a good new smaller overlapping headsail. I know, for many, overlap is like male performance, bigger is better. But in truth, increasing overlap provides little or no increase in speed, except at very low wind velocities - below 6 - 7 knots true - so all that extra overlap provides nothing other than drag and heeling moment. I used the data logging feature to record wind speed, wind direction and boat speed to create a set of polars for my old IOR boat and was stunned to see that a 105% jib had equal to or even better than a 135% on every point of sail, and in every wind velocity except in the very low wind ranges. And in all honesty, if you are a real cruiser, when the wind gets down to 6 knots, the iron genoa gets started anyway. So you lose nothing.

Some other advantages of small overlap headsails:
1. Lower cost
2. Far, far easier to tack
3. Better visibility
4. Better reefability

So just a though, chuck the lead and make your sailing easier with a smaller overlapping headsail, and maybe faster with a smaller headsail.

[HappyMdRSailor]

Originally Posted by denverd0n

A boat is not like a chinese menu... One from column A, one from column B, mix and match however you like. It is a system, where everything works together. Change one thing and it affects everything else. Do you fully understand what all of those other effects will be?

If you're not a qualified naval architect, who understands all of the interactions involved in yacht design and can work out all of the engineering formulas, then this kind of a dramatic change is a complete crapshoot. Maybe it will work out great, or maybe it will be a disaster. Possibly even a seriously dangerous disaster.

Do you really want to take that chance? Your choice, of course. Personally, I would just sell the boat and buy one that was actually designed to function the way that I want it to, rather than trying to redesign and rebuild a boat that is fundamentally unsuitable to my needs to begin with.

Mee Sink You Right DenverSon...

Originally Posted by TxMarineRepair

I would like to suggest a completely different approach. Since the only stated reason for your proposed change is to add stability, why not just reduce the heeling forces. (Full disclosure - I am a sailmaker as well as an owner of an old IOR boat that is tender too). If I were in your shoes, I would:
1. Remove all the loose lead from the bilge and sell if for scrap. At about $.50 per pound you get $500. The boat will be lighter (and in theory faster on most points of sail) or at least you will have compensated for 1000# of cruising gear you have put aboard.
2. Then I would look into a good new smaller overlapping headsail. I know, for many, overlap is like male performance, bigger is better. But in truth, increasing overlap provides little or no increase in speed, except at very low wind velocities - below 6 - 7 knots true - so all that extra overlap provides nothing other than drag and heeling moment. I used the data logging feature to record wind speed, wind direction and boat speed to create a set of polars for my old IOR boat and was stunned to see that a 105% jib had equal to or even better than a 135% on every point of sail, and in every wind velocity except in the very low wind ranges. And in all honesty, if you are a real cruiser, when the wind gets down to 6 knots, the iron genoa gets started anyway. So you lose nothing.

Some other advantages of small overlap headsails:
1. Lower cost
2. Far, far easier to tack
3. Better visibility
4. Better reefability

So just a though, chuck the lead and make your sailing easier with a smaller overlapping headsail, and maybe faster with a smaller headsail.

+1 Answer

[Cadence]

Originally Posted by col blumson

I have about half a ton of lead just sitting under the floor and should be tried in at least.
But the boat 1980 IOR ex racing yacht, is a bit tender thus it should be at the bottom of the keel. I propose to drill through the bottom of the keel put SS rods through protruding so that I can cast the lead around the base of the keel, I would mould the base to be round and shaped as a bulb but flat on the top. Thus some what a fined keel.
Any one with some thoughts would be great to hear.
thanks silly old Col

I'd leave it in the bilge. I would agree with Delmerry about worrying that the keel bolts, hull or rigging won't take it.

Since you said it was onboard already I would leave it in the bilge. Hanging on the keel is going to make a drastic change in your GM. You may end up with a stiffer boat than you want?

[Cheechako]

How much do you really think you would add? a 1000 lbs 6 ft down would be a heck of an additional lever arm... a couple hundred lbs would likely do a lot and really not be much change on the bolts etc. But then, I'm not a firm believer that boats are as highly engineered as some think. it may be more of a "how many bolts can I fit in the bilge connection" design than actual numbers crunched... lets face it... in theory probably one bolt will lift the whole boat... but Murphy intervenes so designers put in many... etc etc...
Every 100# 6 ft from the Vertical CG is like 600 lbs effect....

[gah964]

this idea sound like an episode from startreck its just plain "out there" lol

[gah964]

[QUOTE=Cheechako;1630144]How much do you really think you would add? a 1000 lbs 6 ft down would be a heck of an additional lever arm... a couple hundred lbs would likely do a lot and really not be much change on the bolts etc. But then, I'm not a firm believer that boats are as highly engineered as some think. it may be more of a "how many bolts can I fit in the bilge connection" design than actual numbers crunched... lets face it... in theory probably one bolt will lift the whole boat... but Murphy intervenes so designers put in many... etc etc...
Every 100# 6 ft from the Vertical CG is like 600 lbs effect....[/QUO

your right most bolts holding keels are crazy flimsy I wouldn't even chance on starting a hair line crack in the glass.

[rhhmadry]

Originally Posted by TxMarineRepair
I would like to suggest a completely different approach. Since the only stated reason for your proposed change is to add stability, why not just reduce the heeling forces. (Full disclosure - I am a sailmaker as well as an owner of an old IOR boat that is tender too). If I were in your shoes, I would:
1. Remove all the loose lead from the bilge and sell if for scrap. At about $.50 per pound you get $500. The boat will be lighter (and in theory faster on most points of sail) or at least you will have compensated for 1000# of cruising gear you have put aboard.
2. Then I would look into a good new smaller overlapping headsail. I know, for many, overlap is like male performance, bigger is better. But in truth, increasing overlap provides little or no increase in speed, except at very low wind velocities - below 6 - 7 knots true - so all that extra overlap provides nothing other than drag and heeling moment. I used the data logging feature to record wind speed, wind direction and boat speed to create a set of polars for my old IOR boat and was stunned to see that a 105% jib had equal to or even better than a 135% on every point of sail, and in every wind velocity except in the very low wind ranges. And in all honesty, if you are a real cruiser, when the wind gets down to 6 knots, the iron genoa gets started anyway. So you lose nothing.

Some other advantages of small overlap headsails:
1. Lower cost
2. Far, far easier to tack
3. Better visibility
4. Better reefability

So just a though, chuck the lead and make your sailing easier with a smaller overlapping headsail, and maybe faster with a smaller headsail.



Ding Ding Ding we have a winner!

[barnakiel]

I think #2 has it.

Do not.

b.