Bow thruster on a Sisu 22

sockeye

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I boat on a fast tidal river too.
During the boating season, the water stops moving twice a day in the daylight for about 30 minutes.:D
I'm installing a bow thruster on the 27 H&H as part of the refit.
I'll be 67 yrs old next month.
Going forward in years I figure I won't be getting any stronger physically to hussle the boat on and off the docks in the wind and current.!
What model are you installing?
 

Kenneth

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Agree I'll need a mirror to see under the tube. Actually the lift off bow cover in a Sisu bow is fairly large but will probably get smaller once I get in there to work.
Glassing the bottom side of the tube is the real PIA part.

IMG_2746.JPG
 

RobBaker

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Glassing the bottom side of the tube is the real PIA part.
You did a nice job mine will have a little more room underneath but understand the challenges. Drilled the pilot holes today and the unit arrived today need to measure the tube and get a hole saw next.
 

Kenneth

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You did a nice job mine will have a little more room underneath but understand the challenges. Drilled the pilot holes today and the unit arrived today need to measure the tube and get a hole saw next.
I think a hole saw will create an oblong or egg shaped hole due to the curve of the bow. I made a jig out of threaded rod to mark mine, then cut it out with a jig saw, i'm sure there a other ways to do it.

IMG_2729.JPG

IMG_2730.JPG
 

Toolate

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Mine was so close to the point of the hull on the bottom that I put a piece of foam core in there and glassed it all together. Was not able to wrap tube entirely because the clearance was so low but it was totally encapsulated and then I think I laid up like 4 overlapping layers of 1708 tabs all around it plus csm Inside and out then faired it with hull and deck with glass fibers from csm mixed in. If there is core remove it so tube is glassed to hull skin in and out. Fun project once you are past the interior grinding stage.
 

Shor2832

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Mine was so close to the point of the hull on the bottom that I put a piece of foam core in there and glassed it all together. Was not able to wrap tube entirely because the clearance was so low but it was totally encapsulated and then I think I laid up like 4 overlapping layers of 1708 tabs all around it plus csm Inside and out then faired it with hull and deck with glass fibers from csm mixed in. If there is core remove it so tube is glassed to hull skin in and out. Fun project once you are past the interior grinding stage.
Drawing the proper diameter circle on a piece of paper, with center marked, then transferrng to hull makes it easy too.
 

RobBaker

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I think a hole saw will create an oblong or egg shaped hole due to the curve of the bow. I made a jig out of threaded rod to mark mine, then cut it out with a jig saw, i'm sure there a other ways to do it.
My plan is to replace the pilot drill bit in the hole saw with a steel rod. The rod being long enough to go thru the hull on both sides. Go thru 90% on one side then pull it out and get the other side. If this works it should do away with the oblong shape hole.
 

Genius

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My plan is to replace the pilot drill bit in the hole saw with a steel rod. The rod being long enough to go thru the hull on both sides. Go thru 90% on one side then pull it out and get the other side. If this works it should do away with the oblong shape hole.
won't work. the hole saw isn't deep enough.
 

RobBaker

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won't work. the hole saw isn't deep enough.
Genius good post, got me thinking. The standard hole saw is 1 3/4 deep for going thru a 2*4. They make a deeper one FREUD DHS4500 High Performance Hole Saw which is 2 3/8 inch deep which should help me but not resolve the issue you pointed out. Perhaps I can do most of the cut from the outside and finish up on the inside. Time will tell. My tube is small a little over 4.5 inches so that should also help. I'll have my jig saw handy just in case.
 

eglicomet

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Hey Kenneth, can you post photos? I'm doing a minor refit on my old Dyer project and a thruster is on the dream list of upgrades.
I'm putting a side power in my Dyer project and glassing that tube in was a task, your's will probably be worse with less room to work.
 

Brent

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I know I could improve my motoring technique to the dock but I believe a bow thruster could also help. Where we launch is tidal, the current and the Sisu cabin structure catches the wind and pushes us around. I obviously don’t want to slam into the dock and frequently my bow is pushed away from the dock by the time I grab the line.

Has anyone with a smaller boat like a Sisu been able to fit a bow thruster and has it resolved your docking issues? Could be a good offseason upgrade. I haven’t done any measuring to see if a small unit would fit.
My 22 sisu didn't have enough bow in water for one of them.Id practice docking if I was you
 

RobBaker

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My 22 sisu didn't have enough bow in water for one of them.Id practice docking if I was you
Brent I’ve studied this enough to determine that a thruster will work on my boat. Stay tuned to this thread should have a 4.5 inch hole within the next two weeks weather permitting it’s cold out there.
 

RobBaker

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Started the bow thruster hole today on my Sisu 22. Got about 1/2 way thru on both sides. I need to find my jig saw to cut out the top half of the fiberglass hole to make the room to continue the cut on the lower side of the hole. Lesson learned using this hole saw. It likes cutting at full speed with my drill. At a low speed the hole saw bites to much and kicks out.
partial_hole.JPG
 

RobBaker

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why not just do it like everyone else?
Not sure what the prescribed method you’re referencing. I’ve searched and found DIY installers using jig saws, drills, tools with router bits and sawzalls. The real professionals use a monster boring bit which I certainly don’t have in my tool chest.

I believe that I will have a better crafted hole using this hole saw technique. Obviously if this was a larger boat with a 10 inch hole my tool wouldn’t be successful but for a 4 ½ inch hole I think this is the preferred method.
 
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