socalspearit
02-13-2025, 01:33 PM
Hello, this is my first post...
I run a freediving/spearfishing business in southern California and spent four years building a custom vessel specifically for that task--an island hopper for socal. Vessel was designed specifically for great fuel economy, good speed, and excellent running stability and handling in all weather and rough water, particularly following seas. Use profile is not unlike a RIB. Since she was meant to transport divers in wetsuits who are itching to get in the water, static stability wasn't a concern--everything was about shooting the channel in any weather, tucking into a protected cove, and easily getting in and out of the water. There are some design oddities compared to other boats but these were all things that in my experience would make the vessel safer for her use profile (extremely low windage, low bow, open scuppers and large reserve buoyancy, etc). Vessel hull is cold molded western red cedar, carbon fiber, and s-glass, with some white oak structural components. She's specifically designed around a 60hp engine. I had expected her to be a very fast, very wet boat, comfy enough and decent in rough water, and nice enough to look at. Really high speed in flat water was not a concern as there's lots of small vessels on the market that do that already and for me those are useless; I want a high average speed in mostly sloppy water so I'm not limited to perfect days.
540442540443540445
In short, once I splashed her... SHE WORKED! In some ways she far exceeded expectations and in others she let me down. Build quality and look, once I got her out of isolation and into the world I realized was really good. She's no slouch for a 60hp powered but she was a good deal slower than predicted--32kts so far in flat water without any tweaking.. new outboard break-in.. But ride quality was excellent. She's open of course but relatively dry; no appreciable green water dumps in. She just feels good and is smoother than other vessels her class in all kinds of lousy water, able to maintain 20kts - 25kts in seas that would pound everyone to death in a small RIB or Whaler. So overall, I'm very happy with her seakeeping and running performance. But, if you stop she's downright cruel. Static stability was not a big priority in design and it shows :) I figured this would just make boarding from the water easier... and it does but it's so obnoxious to anyone already on the boat. Her center of gravity is ridiculously low and she's built like a submarine so you can't actually roll her or downflood into her bilge areas but she is decidedly not novice friendly, especially when I have more than 1 passenger. She was designed to carry 800 lbs of cargo originally but ended up about 350lbs heavier than I ever imagined she'd be due to scope creep, pride, and inexperience. Total weight with 18 gallons of gas is about 1150lbs, do DLR about 100 and still between 'light and ultralight'. To be viable as a commercial vessel she needs to carry 800 pounds. Of course when running at any speed she's very stable.
I want to improve static stability without affecting her running characteristics, and because I realized her aesthetic is a big part of her value I don't want to lose this. Options are buoyancy collar (turn her into a RIB), block sponsons (fishing boat hack), or winged sponsons/little outriggers (done on superyachts quite frequently but as far I can tell never on a small vessel like this).
I don't want to do the RIB. This design was about getting away from those. Block sponsons would be very easy to fabricate but not be very aesthetic. Winged sponsons would look sexy and be the kind of fabrication challenge I'd enjoy, but I don't have much experience with multihulls so I'm trying to figure out how to do it with minimal interference to her running characteristics.
I only had time for three days/12 hours of sea trials so far but here's some running footage (to see the wake watch in high rez): https://youtu.be/rTC7Vik1J-Q
I'm thinking to maybe build them with a 1 degree angle of attack to just every so slightly lift the stern.... Any thoughts or relevant links?
540437540438540439
I run a freediving/spearfishing business in southern California and spent four years building a custom vessel specifically for that task--an island hopper for socal. Vessel was designed specifically for great fuel economy, good speed, and excellent running stability and handling in all weather and rough water, particularly following seas. Use profile is not unlike a RIB. Since she was meant to transport divers in wetsuits who are itching to get in the water, static stability wasn't a concern--everything was about shooting the channel in any weather, tucking into a protected cove, and easily getting in and out of the water. There are some design oddities compared to other boats but these were all things that in my experience would make the vessel safer for her use profile (extremely low windage, low bow, open scuppers and large reserve buoyancy, etc). Vessel hull is cold molded western red cedar, carbon fiber, and s-glass, with some white oak structural components. She's specifically designed around a 60hp engine. I had expected her to be a very fast, very wet boat, comfy enough and decent in rough water, and nice enough to look at. Really high speed in flat water was not a concern as there's lots of small vessels on the market that do that already and for me those are useless; I want a high average speed in mostly sloppy water so I'm not limited to perfect days.
540442540443540445
In short, once I splashed her... SHE WORKED! In some ways she far exceeded expectations and in others she let me down. Build quality and look, once I got her out of isolation and into the world I realized was really good. She's no slouch for a 60hp powered but she was a good deal slower than predicted--32kts so far in flat water without any tweaking.. new outboard break-in.. But ride quality was excellent. She's open of course but relatively dry; no appreciable green water dumps in. She just feels good and is smoother than other vessels her class in all kinds of lousy water, able to maintain 20kts - 25kts in seas that would pound everyone to death in a small RIB or Whaler. So overall, I'm very happy with her seakeeping and running performance. But, if you stop she's downright cruel. Static stability was not a big priority in design and it shows :) I figured this would just make boarding from the water easier... and it does but it's so obnoxious to anyone already on the boat. Her center of gravity is ridiculously low and she's built like a submarine so you can't actually roll her or downflood into her bilge areas but she is decidedly not novice friendly, especially when I have more than 1 passenger. She was designed to carry 800 lbs of cargo originally but ended up about 350lbs heavier than I ever imagined she'd be due to scope creep, pride, and inexperience. Total weight with 18 gallons of gas is about 1150lbs, do DLR about 100 and still between 'light and ultralight'. To be viable as a commercial vessel she needs to carry 800 pounds. Of course when running at any speed she's very stable.
I want to improve static stability without affecting her running characteristics, and because I realized her aesthetic is a big part of her value I don't want to lose this. Options are buoyancy collar (turn her into a RIB), block sponsons (fishing boat hack), or winged sponsons/little outriggers (done on superyachts quite frequently but as far I can tell never on a small vessel like this).
I don't want to do the RIB. This design was about getting away from those. Block sponsons would be very easy to fabricate but not be very aesthetic. Winged sponsons would look sexy and be the kind of fabrication challenge I'd enjoy, but I don't have much experience with multihulls so I'm trying to figure out how to do it with minimal interference to her running characteristics.
I only had time for three days/12 hours of sea trials so far but here's some running footage (to see the wake watch in high rez): https://youtu.be/rTC7Vik1J-Q
I'm thinking to maybe build them with a 1 degree angle of attack to just every so slightly lift the stern.... Any thoughts or relevant links?
540437540438540439