Author Topic: GA 28 built by Kachemak Skiffs Wasilla, AK  (Read 16812 times)

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Brian.Dixon

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Re: GA 28 built by Kachemak Skiffs Wasilla, AK
« Reply #210 on: July 11, 2020, 07:57:16 AM »

Well ... that's what most people in Alaska and the Pacific Northwest do.  Set it up to be the highest it can be for average planing conditions, then drop it a hole. .. more or less cav plate submerged by 3/4".  Renn put a hydraulic jack plate on his Jumbo and experimented ... trying to max his efficiency / mileage.  His conclusion is that the jack plate didn't help much - immeasurable difference in mileage, if any.  But what he DID say was that having a hydraulic jack plate was super hand for when you get grounded on a bar ... raise the motor as far as possible and motor off the bar while passengers push!  Been there, done that, and it doesn't take much of a grounding to be stuck pretty good.  If it were me?  I'd buy a hydraulic jack plate, be glad to have it, and just get a short one that keeps the outboard close to the transom.  Just my personal opinion ... 99% of the people with Great Alaskans go without a jack plate.  Getting stuck once might change your mind.

Brian

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Dan Boccia

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Re: GA 28 built by Kachemak Skiffs Wasilla, AK
« Reply #211 on: July 12, 2020, 01:40:04 AM »
Just finished re-mounting the engine and the learning continued. I waited 2 days for the paint to get decently dry after patching the transom up. This was a case of "good enough" for finish since nobody will see anything under the engine mount. While the paint was drying I did more research and found one article and one video that were very informative about how to set the height of your outboard.

Starting around 3:30 in this video, these installers at a high-volume shop talk about engine height very clearly:
https://www.youtube.com/watch?v=N_EMx9WwTlY

This article also has some very useful info:
https://www.boats.com/how-to/the-outboard-expert-boost-speed-with-outboard-engine-height-adjustments/

My Suzuki 250 has its water intakes ~ 6" below the anti-cavitation plate, so there should be no worry about getting cooling water.

Basically, the article and video and other sources I consulted agree that the engine's anti-cav plate should be level with the bottom of the boat or an inch or two higher. What I found is that my engine shop set the anti-cav plate even with the bottom of the 3/4" thick UHMW keel strip of my boat, rather than the actual flat portion of the bottom panels. Going up only one hole still left the anti-cav plate lower than the boat bottom, so I went up 2 holes and ended up 5/8" higher than the bottom of the boat, which seems like a good starting point for my tests. With the engine trimmed so the anti-cav plate is parallel with the boat bottom, the front of the prop is 22 1/2" from the transom, and I have to think that the water flowing past the transom will rise at least 5/8" in almost 2 ft.

Heading to Homer again this coming week for more solar installations, so will be able to give it a thorough test. I have a feeling I will not have to trim the engine all the way down as I had to before, and that I'm going to get much closer to 6100 rpm at full throttle, which means I can go with a higher pitch prop (sweet spot on rpm is 5700-5800 rpm), which means more efficiency. It's going to be interesting!
« Last Edit: July 12, 2020, 01:40:58 AM by Dan Boccia »

Brian.Dixon

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Re: GA 28 built by Kachemak Skiffs Wasilla, AK
« Reply #212 on: July 12, 2020, 09:01:27 AM »

I hadn't seen the first link (video), but have seen the second.  Most Great Alaskans will need the 'normal' height since they are not a speed boat, often need 'grunt' at slow speeds to respond to the seas, e.g. turn hard and fast into an incoming wave, yet ... still have a need to run fast when conditions allow.  I'm looking forward to hearing your results with the 5/8"-high setting ... might not be a bad idea since most fishing/camping boats get heavy in the stern when loaded for a trip and when people are fishing etc.

Brian

PS: Your paint job looks great from here ... :D
The Great Alaskan - Professional grade offshore performance - Designed to be built by anyone! - https://www.glacierboats.com  ><((((> .`.><((((> .`.><((((> .`.><((((>

Dan Boccia

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Re: GA 28 built by Kachemak Skiffs Wasilla, AK
« Reply #213 on: July 20, 2020, 10:25:08 PM »
I've only had the boat out once since raising my engine up 2 holes, in a mixed-up 4-ft sea, so was unable to do any proper testing. However, having a buddy run the helm, I ran back and eyeballed the anti-cav plate's position relative to the water, and with a wide range of engine trim and on-plane speeds, the anti-cav plate was always just out of the water. There was a lot less random spray in the area, and it always had a full stream of cooling water and the engine ran cool. So for my build, 2 holes up on the outboard is looking spot-on. More tests when I get a calmer sea to operate in.

On another note, I've done the 4+ hour one-way drive between Anchorage and Homer 4 times now, and my 4Runner with a 7000 lb towing capacity continues to impress me. Up over 2 minor passes, speeds up to 70mph, and the 4Runner runs smooth, having to run at 4200 rpm on the strong pulls, but usually running between 2-3000 rpm and staying cool. So my goal of building light enough to be able to use my existing tow vehicle appears to have worked. Brakes on both axles of the trailer is helpful and comforting.

Finally, there has been some banter about mounting various battery chargers in the bilge compartment, as I have done with my Sterling battery-to-battery charger. I've advised a few people to move their non-ignition-protected devices out of that compartment. The Sterling IS ignition-protected, as is the Blue Seas battery switch I also have in there, so my installation is safe. Very few, if any, of the other manufacturer's charging solutions are ignition-protected, so that is something to look for. Gas fumes emitting from the fuel hoses WILL build up in the bilge, and anything mounted in there needs to be ignition-protected.

Djeffrey

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Re: GA 28 built by Kachemak Skiffs Wasilla, AK
« Reply #214 on: July 21, 2020, 07:15:07 AM »
If you get a chance take video of your engine running out. It would be nice to compare how my water flow compares to yours. Ill do the same

Dan Boccia

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Re: GA 28 built by Kachemak Skiffs Wasilla, AK
« Reply #215 on: July 21, 2020, 11:23:00 AM »
Dennis that's something I've been thinking of doing. Once I get the right conditions and a buddy or two on board I'll do just that.

Dan Boccia

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Re: GA 28 built by Kachemak Skiffs Wasilla, AK
« Reply #216 on: August 10, 2020, 03:05:37 PM »
Finally finished the dinette bunk extension and boot storage in my wet gear locker, which is one of the most useful features of the boat for sure (way more useful than a head!). Warm air comes in from the bottom port forward corner of the locker, and vents out the upper starboard aft corner. Any water runs out the limber hole to the back deck. Just added these ABS boot trees. Since figuring out how to outfit these fussy details took a lot of my time while designing/building the boat, I'm posting lots of details for future builders. I have plans for a 16" tall by 18" wide by 8" deep "glove box" right above the cleat for the dinette bunk extension, and a smaller shelf immediately above the warm air duct to protect the duct and add to storage options. These 2 storage units will also hide the cable to the port V-berth light.

Todd j

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Re: GA 28 built by Kachemak Skiffs Wasilla, AK
« Reply #217 on: August 10, 2020, 07:32:40 PM »
So many nice touches.  Ive often wondered how you deal with your changes/additions to what appear to be a finished boat.  They are well thought out

Brian.Dixon

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Re: GA 28 built by Kachemak Skiffs Wasilla, AK
« Reply #218 on: August 11, 2020, 06:16:35 AM »

Where's the flat screen TV and blueray player going to go?  :D

Looks fabulous!  Best wet locker I've seen!

bd

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Djeffrey

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Re: GA 28 built by Kachemak Skiffs Wasilla, AK
« Reply #219 on: Today at 08:33:25 AM »
Nice job on the dry locker. Great idea!