Anonymous wrote:

Jonny Kaplan wrote:

Hi everyone, 

I've recently become the steward of a very nice 1977 , Compass H28 here in The San Francisco Bay Area. I'm very impressed with the way this boat is put together. She obviously sailed to San Francisco from New Zealand at some point.

Of course , my thoughts are immediately "let's junk her!" , but in the USA , the costs of masts are always prohibitive. That being said , I MAY have a line on an affordable flagpole. Going by Arne's old  design here , I need roughly 36-37 ft. 

The flagpole in question is approximately 7" at the bottom , tapering to approx. 3.5" at the top , which seems to be pretty good. 

The wall thickness is .188 " . THIS ..... is the big question. 

Do you think the wall thickness is strong enough?? 

thanks,

Jonny

Jonny, That is only 3mm wall thickness and it is not strong enough.  You need 5mm, and also probably a minimum of 200 dia at the partners, with 110mm at the truck.  That's what I had on Arion and it was very robust.  I sympathise with you.  It is impossible to find an alloy section of those specs in Australia, too.  Arion's mast section was imported from France.

Hey Graham!

Ahh ... thats what I was afraid of.  Back to the drawing board!

Question: 110 mm at the truck . What is the truck? The top?

thanks.

J

Anonymous wrote:

hi jonny

Jonny Kaplan wrote:

…The wall thickness is .188 " . THIS ..... is the big question. 

i just inserted the data of the mast and the hull into this calculator. it calculates a breaking strength of 1.8 times the righting moment of this hull.

i don't know what type of alloy your flagpole is made of (and i don't know which alloy is the base of oscar's calculator…) – and the righting moment of the hull is a rough guess based only on its weight and beam.

…but it tells me, that the flagpole might be good for cruising in sheltered waters but maybe not for serious cruising across oceans…

ueli

Thanks Ueli!,

The pole is Aluminum. I wasn't aware of Oscar's calculator. I'll have a look at that later today.

J

Hi everyone, 

I've recently become the steward of a very nice 1977 , Compass H28 here in The San Francisco Bay Area. I'm very impressed with the way this boat is put together. She obviously sailed to San Francisco from New Zealand at some point.

Of course , my thoughts are immediately "let's junk her!" , but in the USA , the costs of masts are always prohibitive. That being said , I MAY have a line on an affordable flagpole. Going by Arne's old  design here , I need roughly 36-37 ft. 

The flagpole in question is approximately 7" at the bottom , tapering to approx. 3.5" at the top , which seems to be pretty good. 

The wall thickness is .188 " . THIS ..... is the big question. 

Do you think the wall thickness is strong enough?? 

thanks,

Jonny