Length of gains for lapstrake hull

[gkharrin]

Does anyone have references documenting one or more ways the length of the gains for a lapstrake hull is determined?

I found the forum post below that states it is only the last foot.  General web searches show various instances between 18" and 30", but nothing as short as 12".  I also have a reasonably strong recollection of reading "20 x the plank thickness", but I cannot locate that reference now.  The planking is 7/8", so 20 times this would be ~18", putting it in the ballpark of what I found online.

 

If it makes a difference, the subject of my boat is late 19th-century Danish. 

 

Thanks,

Greg

 

 

[druxey]

For small boats 12" to 18" seems to be the range.

[gkharrin]

6 hours ago, druxey said:

For small boats 12" to 18" seems to be the range.

 

Thanks, Druxey.  If it matters, this is a fishing vessel about 30 feet long with a beam of approximately 10 feet.

[druxey]

I'd go with 12", gk.

[wefalck]

I would dare say that it also depends on how rounded the boat ends are. Don't have access to it at the moment, but didn't Eric McKee say something about this in: MCKEE, E. (1980): Clenched Lap or Clinker.- 30 p., Greenwich (National Maritime Museum).

 

 

[gkharrin]

8 hours ago, wefalck said:

I would dare say that it also depends on how rounded the boat ends are. Don't have access to it at the moment, but didn't Eric McKee say something about this in: MCKEE, E. (1980): Clenched Lap or Clinker.- 30 p., Greenwich (National Maritime Museum).

 

 

 

Thanks for the post and the reference.  I looked up "Clenched Lap or Clinker", and it is intriguing.  I investigated getting a copy, but the best price is $35 and it is only 30 pages.  I may wait for another opportunity.

 

The stern on this boat is very rounded.  But the difference in overall bend is just half the thickness of the plank (if using half laps), so I'm not sure how much a factor the shape is. 

 

I forgot about some photos online of a replica being built.  I may be able to scale off an approximate length, but it is hard to determine where the taper really begins.  I'll post again later.  Now back to my real job....

 

 

[Jaager]

Being that this is a Scandinavian lapstrake vessel,  it has a long line behind it.   Is there not physical evidence of antecedent  clinker methods from the 800-900's?  The outside limits for land length could reside there.   I would bet that a concerted effort was made to maintain a link with that past in how this later vessel was designed and built.

[rcweir]

I have a copy of McKee and he says 9 inches.   He terms it chasing, where  a sloping rabbet is cut into the top edge of the strake below the one being installed.  At this point he's talking specifically about his 10' example boat.  I haven't found anywhere that he gives more general guidance on chasing, though he does mention that there are other ways than a sloping rabbet to get the plank end down so it can fit into the stem or stern rabbet.  I don't think I have the terminology completely figured out, but the 9" measurement is definite for his 10' boat.

 

The McKee is a pretty neat little publication.  It includes a card half-hull model of his 10' example boat.