Hi,
I have been researching multi designs to build for a while now (Wharram, Woods, Kellsell,
Shuttleworth & Farrier) and really like the Harryproa concept. It just seems to me that there
is not much space in them for their size. So I have a few questions regarding their design.
To say there is not much space for their size is looking at them from the wrong direction and missing the point of Harryproas. There is a growing trend with modern multis, particularly cats, towards fitting too much in a given space. It is ostensibly waterline length that gives performance and beam which gives you righting moment allowing greater sail carrying capacity. Catamarans inherantly have a large footprint allowing good performance but designers are under intense market pressure to fill this extra space with living accomodation and comfort leading to boats that are becoming unaffordable and no longer perform. At Harryproa, we start off with a given amount of accomodation and design the amount of boat needed to give that accomodation suitable performance. Thus you end up with a long wide boat with the benefits of very good performance, light weight, economical to build and safe, easy handling. As it happens you do also end up with a great deal of accomodation and useable deckspace. Most people are amazed at how much space there is in the ww hulls. Comfort, price and performance is the triplet not available in other designs.
Why does the accommodation hull need to be so narrow down low? Could a Harryproa be
built with an accommodation hull like the centre of a trimaran, or at least more flared.
There would be little more wetted area, but bouyancy would be improved as would living
area inside. Is it because of slamming or wake interference between the two hulls?
We have considered flaired hulls but decided they're not necessary on the present models. The L/B ratio of Harryproa leeward hulls are very high at around1:20, which gives us performance. The windward hulls have a lower L/B but must be kept reasonably high to avoid excessive drag. The balance is to provide enough buoyancy and space inside while not slowing the boat. We feel the waterline widths chosen have given us this balance, maintaining adequate accomodation. Flairing the ww hull makes building more difficult, increases weight and makes coming alongside more dificult, as well as creating the potential to carry more 'junk'. Again, we are avoiding the trend to fit too much accomodation into a given space.
Why does the accommodation hull need to be so narrow down low? Could a Harryproa be
built with an accommodation hull like the centre of a trimaran, or at least more flared.
There would be little more wetted area, but bouyancy would be improved as would living
area inside. Is it because of slamming or wake interference between the two hulls?
We have considered flaired hulls but decided they're not necessary on the present models. The L/B ratio of Harryproa leeward hulls are very high at around1:20, which gives us performance. The windward hulls have a lower L/B but must be kept reasonably high to avoid excessive drag. The balance is to provide enough buoyancy and space inside while not slowing the boat. We feel the waterline widths chosen have given us this balance, maintaining adequate accomodation. Flairing the ww hull makes building more difficult, increases weight and makes coming alongside more dificult, as well as creating the potential to carry more 'junk'. Again, we are avoiding the trend to fit too much accomodation into a given space.
The bridgedeck area from what I have read is not of standing head room height. Could the
height of the mast boom be raised to allow for more height in the bridge deck or would
this adversely affect windage and or righting moment?
height of the mast boom be raised to allow for more height in the bridge deck or would
this adversely affect windage and or righting moment?
The bridgedecks does have full standing headroom on all our models although you do need to duck when shunting the Harry. The Harry also has full headroom in the cockpit with the poptop up. The cruising Visionarry has has full headroom throughout.
Could the lee hull be flared more at the top to provide more useable bunk space when
visitors are aboard or for crew if the boat were put to charter work?
Could the lee hull be flared more at the top to provide more useable bunk space when
visitors are aboard or for crew if the boat were put to charter work?
Possibly. Robert has also suggested this but we would need our engineer to investigate how this would affect the torsional loads.
Sorry if these have been canvassed before, it's just I couldn't find the info.
We are always happy to answer questions.
Love the designs, just love the simplicity, keep up the good work.
Love the designs, just love the simplicity, keep up the good work.
Glad you like them. We too love the simplicity and hope to keep them that way.
Cheers,
Mark
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