Plumb bow stupidity

Stemar said:
Personally, I like the idea of the bow lifting and keeping the waves in the sea where they belong, and not trying to wash me off the foredeck. I don't go sailing to get places quickly.
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Because decks were drier in the old days? Try again, modern boats have much drier decks as they also don’t come down and under the waves after rising up!
geem said:
These days with wafer thin grp hulls its not quite the same. Not seen many oil tankers or commercial ships with straight bows. That racing waterline thing still seems to be popular in commercial ships😅
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Never seen significant damage from an anchor just light scratches. Have seen many large ships with plumb bows to the waterline, but the usually have a bulb under it.
 
lustyd said:
Because decks were drier in the old days? Try again, modern boats have much drier decks as they also don’t come down and under the waves after rising up!

Never seen significant damage from an anchor just light scratches. Have seen many large ships with plumb bows to the waterline, but the usually have a bulb under it.
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I also have never seen significant damage from an anchor. Just lots of dings. I would rather not have dings if there is a choice.
I don't see any evidence that plumb bows are drier. Modern cruisers seem to have great freeboard than older desgns. I suspect this keeps the decks drier. Our old design also has high topsides and is a dry boat as a result of that.
Doing a bit of research on yacht design sites it would appear that the school of thought with plumb bow designs is that the lack of reserve buoyancy that a plumb bow has, has to be compensated for by adding more fullness in the bow. This also helps with increasing the accommodation space. The drawback on cruisers is the fuller plumb bow leads to slower performance in tougher windward conditions. One article suggested that this was an acceptable trade off in modern cruisers as most people simply put the engine on to go upwind. Sort of makes sense.
 
geem said:
Doing a bit of research on yacht design sites it would appear that the school of thought with plumb bow designs is that the lack of reserve buoyancy that a plumb bow has, has to be compensated for by adding more fullness in the bow. This also helps with increasing the accommodation space. The drawback on cruisers is the fuller plumb bow leads to slower performance in tougher windward conditions. One article suggested that this was an acceptable trade off in modern cruisers as most people simply put the engine on to go upwind. Sort of makes sense.
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It's also not backed up by observed performance. A well designed full bow section is actually quicker to windward in the heavy stuff than a narrower boat. It's the light wind performance that suffers.
 
Everything I’ve ever read that said similar was based on waterline length rather than boat length, and so of course the modern 36 footer with a 36 foot waterline does worse than and old 46 footer with a 36 foot waterline length into the wind. For LOA you’re better with the modern design as it doesn’t need to heel to get speed
 
As I understand it, LWL becomes a limiting factor specifically when approaching hull speed. In lighter conditions wetted surface area becomes more significant.
 
Kelpie said:
As I understand it, LWL becomes a limiting factor specifically when approaching hull speed. In lighter conditions wetted surface area becomes more significant.
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Basically.
However when going upwind it’s also about standing up to your sail, and that’s where wider bow sections can help if done correctly.
 
geem said:
. Modern cruising boats designs are not out right fast.
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Many are, if one compares them to their predecessors. Modern yachts do TEND to be faster on a comparible basis. That is if one can decide what is comparible, of course. But I would match my 31 ft Hanse against, say, a Moody 31 or a Sigma 33; or a Hanse 345 against a UFO 34. Different sea keeping qualities, but the Hanse will be drier, roomier & miles faster. But I doubt that I could beat the old half tonners like Stephen Jone's Tumblehome. Simply because it is a race boat , not a cruising boat.
You are comparing them to race boats. If you compare a modern family car to an older family car the modern one would normally be considerably faster. but you would not compare the modern family car with the modern racing saloon car would you.
 
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geem said:
I just watched a Beneteau 41.1 charter boat lifting it anchor. The anchor came up upside down so the girl on the bow let it down again and is smacked into the hull. She powered the windlass up and it came up upside down again. She lowered it again and banged the hull hard for a second time. Who thought it was a good idea to have plumb bows? If you have an extended bow roller to place the anchor further forward the offerings from the production boat manufacturers are often pretty flimsy affairs.
We have a traditional raked bow with a massive bowroller. We often bring up the anchor and it's full of mud or sticky sand. We dangle the anchor at the surface and motor along at low revs to clean the anchor. How do you do this with a plumb bow?
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Called progress😏
 
The preponderance of fixed bowsprits on new boats jinxes the waterline length discussion.

For example the new First 36 does indeed have a long waterline on it's 36 foot hull - but the boat is actually over 3 foot longer. That metre costs in a marina.

A long overhang forward looks good, helps in waves, prevents anchor damage increases deck space and the accommodation underneath it is far more useful than the fresh air under a bowsprit. Mine houses the anchor gear, some storage beneath and two pair of sleeper's feet.

.
 
doug748 said:
In my opinion A long overhang forward looks good, helps in waves, prevents anchor damage increases deck space and the accommodation underneath it is far more useful than the fresh air under a bowsprit. Mine houses the anchor gear, some storage beneath and two pair of sleeper's feet.
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fixed that for you :)
 
Daydream believer said:
Many are, if one compares them to their predecessors. Modern yachts do TEND to be faster on a comparible basis. That is if one can decide what is comparible, of course. But I would match my 31 ft Hanse against, say, a Moody 31 or a Sigma 33; or a Hanse 345 against a UFO 34. Different sea keeping qualities, but the Hanse will be drier, roomier & miles faster. But I doubt that I could beat the old half tonners like Stephen Jone's Tumblehome. Simply because it is a race boat , not a cruising boat.
You are comparing them to race boats. If you compare a modern family car to an older family car the modern one would normally be considerably faster. but you would not compare the modern family car with the modern racing saloon car would you.
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We don't cruise like that. Very few do out here in the Carabbean as we are all liveaboards. Boats carry far more gear than weekend cruisers. Take a typical 38 to 45ft cruiser over here. The modern production boats are often sat at anchor with no bottom paint showing. Their flat bottom hull shapes are not great for carrying weight. With all the food, fuel, water, spares, paddleboards, bikes, rib and large engine, solar arch, etc the once sprightly weekend cruiser is now a slug. They drag their long waterline sugar scoop under water and they are slow. Its a great leveler that sees older designs with higher weight carrying potential on a par or faster than their modern counterpart. Only when you get to the 50+ foot boat do you see this trend disappear.
 
geem said:
We don't cruise like that. Very few do out here in the Carabbean as we are all liveaboards. Boats carry far more gear than weekend cruisers. Take a typical 38 to 45ft cruiser over here. The modern production boats are often sat at anchor with no bottom paint showing. Their flat bottom hull shapes are not great for carrying weight. With all the food, fuel, water, spares, paddleboards, bikes, rib and large engine, solar arch, etc the once sprightly weekend cruiser is now a slug. They drag their long waterline sugar scoop under water and they are slow. Its a great leveler that sees older designs with higher weight carrying potential on a par or faster than their modern counterpart. Only when you get to the 50+ foot boat do you see this trend disappear.
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How many threads are you going to create trying to tell everybody only boats like yours are any good?

Glad you enjoy your boat. But perhaps shouldn’t rant on about other types of boats for which you seem to have limited experience.
Or surf too many very selective “boat design websites” that are full of self confirming bias, rather than much diverse and scientific data.

These posts are just full of generalisations, many/most not backed by facts - eg “Flat bottom hull shapes are not great for carrying weight”. Tell that, posthumously, to the designers of Thames barges, for example.
 
To be fair he's right. Modern boats with all that stuff on are slower. What he didn't say is that an older boat of the same length couldn't fit all that stuff in, probably not even half of it, and that's the real reason they sail higher in the water. He was, in fact, agreeing with you I think that all things being equal the modern boat is faster. Hence creating a scenario where the modern boat could lose - filling up the ample living space and storage to the brim ;)
 
Working fishing boats do haveplumb bows but in the main they don’t anchour a lot and need to get in crowded ports(or used to). What is the advantage of a plumb bow in a yacht,In the very successful 26 footed Stephen Jones used. Plumb narrow bow and had to raise the topsides to get bouyancy((sadler26)
 
lustyd said:
To be fair he's right. Modern boats with all that stuff on are slower. What he didn't say is that an older boat of the same length couldn't fit all that stuff in, probably not even half of it, and that's the real reason they sail higher in the water. He was, in fact, agreeing with you I think that all things being equal the modern boat is faster. Hence creating a scenario where the modern boat could lose - filling up the ample living space and storage to the brim ;)
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You are not far off. Modern boats have far higher volume length for length. They have way more accommodation. No dispute there. Length for length with a modern bavaria, Jen or Ben we have larger water tanks, larger fuel tanks, far higher storage but that wasn't the point. We are way heavier than the modern cruiser of the same length before we put all the toys onboard. This thread didn't start off about modern vs old. It was about the idiocy of plumb bow for a cruising boat but I should have been more specific. A cruising boat that anchors a lot and doesnt go from marina to marina as a pastime. If you never anchor then having a good anchor set up is clearly not an issue. I linked an article in Practical Sailor in post 12 that I think is well balanced and looks at the pros and cons. There is really no thing more to say
 
I would imagine that tpc (tonnes per centimetre immersion) on older boats increase with increasing draft (flared topsides, counter stern, spoon bow) whereas more modern slab sided vessels would have a smaller increase as draft increases. Immersing the knuckle where the transom turns to bottom is the killer, nothing to do with the bow. Once you immerse the transom, you generate a large wake and that saps energy.

Sailing up right is good - maximising sail area and foil effectiveness which favours those hulls with larger form stability, which in turn allows less ballast, lighter boat which is faster. So it should be no surprise that modern sled is quicker than a wine glass. Perhaps not so comfortable in a seaway or at anchor in a swell.

I do wonder what really sells boats to the majority. I have vague memories of going to the LBS, big halls with big (for the early 80s) boats lined up. Is it not the inside that sells boats to most people? It’s not always easy to see the outside of a boat at a show or in a marina so external aesthetics are less important. Plumb bows (to me at least) are nice on a Zulu, Fifie or a Thames barge but ugly in plastic, but they do give internal volume in a part of the hull which has always been cramped. Internal volume sells boats.

I suspect plumb bows in cruising boats are about internal volume. It’s convenient that a full plumb bow is trending in racing boats where it helps to lift them onto the plane so helps the marketing
 
I had a nearly plumb bow on my PDQ for a decade and I never dinged the bow (see avitar). Just don't motor forward while recovering. Obvious. Just sit still or drift back slowly, very easy, no problem.

Charter boaters are not a true example.
 
thinwater said:
I had a nearly plumb bow on my PDQ for a decade and I never dinged the bow (see avitar). Just don't motor forward while recovering. Obvious. Just sit still or drift back slowly, very easy, no problem.

Charter boaters are not a true example.
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You have a cat. Presumably the windlass is in the middle away from the bows?
 
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