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Hi All
I have few more questions about the build.
1) is a good idea to add backgrounds mg for the back handles? Also which is better metal or mesh?2) do u still need a motor wedge if you are using thrust bracket? If so, how wide do it need to be?
3) should I added the aluminum back plating? When do I get it at?
thanks in advance,
Andy
We screwed our handles into parts of the transom that were doubled. With the wisdom of hindsight, they should be farther apart, but we’re not moving them.
The bow handle should also have some backer, which we installed before the deck went on. We epoxied strips of wood to both sides of the longitudinal frame under where the handle would mount.
The following notes apply to our Tohatsu installation. We know nothing about doing it with any other motor, and we’re learning as we go with the Tohatsu.
Wedge for Tohatsu should be at least 7 inches. A bit wider might make it easier to work with.
Aluminum back plate won’t easily work with the thrust bracket. We have one (12 x 12 x 1/4-inch) if someone wants to buy it at cost, $30.
Before you put the deck on, install wood backers everywhere you might want to attach anything to the cockpit sides.
Jack and I got the Tohatsu motor (a whole other story) long after boat construction was finished. The remote control is big and heavy enough that it was not feasible to just screw it into the thin plywood. We made a hole for a 4-inch inspection port just to the rear of the remote control location, and reached in to attach the screws. The whole process for this was hours and hours of aggravation.
Some pointers for anyone who does this:
Take frame members into account if you cut a hole. Also take into account the fact that the heavy cable from the Tohatsu control will come straight out of the rear of the control box. They cross directly over our inspection port, but it works, more or less.
Take the available length of your arm’s reach into the hole into account. Trust me. About 12 inches was as much as I could manage, and everything in there had to be done by feel. Imagine fumbling for 2 to 10 minutes for each washer and nut you want to install. I used stainless M6 wing nuts to make it a bit “easier”, then held them while jack turned the screws.
If you decide to use threaded inserts, be aware that they need to be aligned VERY accurately or you won’t be able to get the screws in. If you want to do it anyway, McMaster-Carr has stainless M6 inserts. We ended up using one of them and gave up after that. We have two left if anyone wants them.
If I had to do it with inserts, I’d put the bolts through the control box, jam-nut the inserts in place on the ends of the bolts, and use that to mark the holes and turn the inserts in. That’s just an idea that came to me later.
If we had to mount the remote control box again, we’d replace the M6 bolts with large (#14?) stainless flat or oval head wood screws of a suitable length and diameter. If there’s enough thickness of wood epoxied to the back of the cockpit side, you can drill and screw right into it, it’s easily removable, and MUCH LESS work than what we did.
Finally, the Brown thrust bracket will NOT work with a kit boat for two reasons, which I won’t go into now. Jack and I are modifying it to work with our kit boat.
Jack and I will be at the race on 24 July 2021, wearing “150” tee shirts if you want to find us and discuss. We’ll have the wedge and thrust bracket with us, but not the boat.
Hey Marty, thank you word of advice. I have not put the lid on the boat yet (next step). I will add backer board to bow area for the handle. One question, how long is the wedge you made?
Thanks again for help,
Andy
How long is the wedge (top to bottom)? That is a good question and will require a long answer explaining how we got to this point. I apologize for not posting photos, but I’ve had no luck with doing that here recently.
Per instructions from Alan Brown, I had a wood shop make a 10-degree wedge. The wedge was sized to fit under the Brown 4095 thrust bracket base plate, from the angle to the top. The base plate is bent to a 10-degree angle to fit around the wedge. The top of the base plate is flush with the top of the transom. I don’t remember the height of the wedge. It should be at least 7 inches wide, but a bit wider might be useful. You can always trim it.
We ran into several interconnected issues with the Brown thrust bracket on our CLC kit boat. Note that the photos on his web site show the prototype on a boat with the transom built to an angle without a wedge and without a drain plug at the bottom.
The base plate of the thrust bracket from top to bottom is equal to the full height of the transom, i.e. the bottom of the base plate is flush with the bottom of the transom (and the top is flush with the top of the transom, as mentioned).
Problem number 1a: There is a protruding drain plug just off-center on the kit boat. The base plate cannot mount over the drain plug.
Problem number 1b: The thrust bracket needs to sit close to the bottom of the transom to land in the intended location just beneath the cavitation fin, so cutting off the bottom of the base plate is not a solution because then there’s no support directly beneath the bracket.
Idea for solution 1a: Close off the drain hole during construction and relocate the drain a few inches farther away, but still in the same cavity. This is not hard to do if you haven’t installed the cockpit floor yet. Cut a plug of plywood to fit the hole, epoxy a wood backer behind the hole, and epoxy the plug into the hole.
Idea for solution 1b: Place the thrust bracket on top of the cavitation fin instead of beneath it. This is complicated by a not-quite-flush rubber plug on the propeller shaft that will foul the thrust bracket cam. That might or might not be an issue in the real world, but the way around it is to raise the thrust bracket far enough over the fin to clear it, about an inch. Otherwise, I’d worry about that rubber plug being beat up by the bracket.
It seems to me that the physics of raising the thrust bracket will reduce its effectiveness, but it’s still better to have it than to not have it.
BUT …
Problem 2: We discovered that the thickness of the full-height wedge, plus the transom, plus the 1/8-inch bracket base plate, plus the two Brown 10-degree mini-wedges on the front side of the transom (to keep the clamps at the correct angle), was more than the span of the motor clamps, i.e. too thick to get the motor on at all, even if we were able to do something about the drain plug problem at the botttom.
Solution 2a: Keep experimenting with it and see if things can be arranged so the motor clamps will fit. We weren’t interested in fiddling with all those loose parts and a 60-pound motor any longer in a stinking-hot garage and decided to not pursue this.
Solution 2b: Reduce the height of the wedge by trimming the top (the angle stays the same), and reduce the height of the bracket base plate at the top by the same amount. This way, the base plate and the wedge will stay flush with the top of the transom, the top of the wedge is thinner, and it raises the bracket closer to where we need it to be anyway (more about that later).
2b is what we did. We cut approximately 2.25 inches off the top of the base plate and trimmed the top of the wedge to match. This coming weekend, we will install the whole business again for a final confirmation of fit, take some pictures, then take it apart so we can take the pieces to the Pasadena race the following weekend to discuss with Fred Allerton and other Tohatsu owners.
More notes about this process:
There is also the issue of the vertical alignment of the bracket itself. The original thrust bracket set that Alan Brown sent me had a bracket with a base that positioned the bracket low enough to get it below and against the cavitation fin. This is the bracket shown in the photos on his web site. Later, he sent me a bracket base that did not sit low, i.e the base is shorter in height and locates behind the bracket cam. (It looks like the #4005 thrust bracket on his web site.) Combined with the available vertical adjustment from the slots in the bracket base, we confirmed that we could get the bracket at the height we want it after our modifications.
Then there is the issue of the forward to aft alignment of the bracket. Will it end up where it belongs, snug against the propeller shaft? As far as we can tell, from our clamp-on mockups, it looks like it will fit. This is with the motor clamp angle set to the second hole from the lowest on its pivot, which makes it more or less parallel to the transom when mounted with a 10-degree wedge. Note that this is with the shortest side plates that Alan Brown makes for the bracket, shorter than those shown on his web site photo.
And finally, there is the issue of the countersunk holes on the base plate. They are intended to screw to the bottom of the motor clamp to attach the base plate to the motor. Apparently the intention is to fasten it to the motor rather than the boat. When you hold it in place against the motor you can see how it is intended to fit. The screws are already in the clamp. With our modification, these holes don’t land in the right place, so we will duplicate them farther down, which will take some careful measuring and drilling.
In closing, these are the points I take away:
1. We want the thrust bracket as a precaution to prevent the motor from breaking the transom loose.
2. The thrust bracket as supplied by Alan Brown won’t work with the CLC kit boat without making changes to it and/or the boat.
3. We have figured out how to modify the bracket to make it fit, but we don’t know how well our changes will work in the real world because we haven’t launched the boat yet.
4. Per Alan Brown, the motor should be strapped down against the thrust bracket to prevent movement in the other direction (and to prevent the cam from sliding out!). We haven’t figured out how to do this yet, but compared to the time spent on the thrust bracket so far, it will be simple.
Sorry this was so long.
Hi Andy,
I put marine plywood backings behind all of my handles. I think that it is a good idea, because between the weight of your boat, the motor and water that is shipped onboard during a race, your boat can get quite heavy.
Regarding the motor wedge, yes, I am sure that you will need a wedge. The angle of your motor to the transom is an important factor to your boat running flat and not porpoising. It is a challenge to get this right and you will find that you may need to make many modifications to your wedge and the adjustment of the angle. I got a lot of help from experienced racers on this and it helped a lot. But I still had to experiment and test, and then had to keep working at it after adding new motors. I rejected the idea of a thrust bracket because I added a 1/4 inch aluminum plate to my transom to add strength. I found my aluminum plate at a local scrap dealer, and have gone back several times for other pieces of aluminum to use on other parts of my boat. I think the aluminum plate has paid off because my boat has not broken in spite of several collisions, one with a submerged piling, and several racing collisions when my boat got smacked on the aft (ass). But the addition of the aluminum plate limited the space between the transom and the motor, so a thrust bracket would not have worked for me. You will find that each builder finds his/her own way to deal with these variables, and we often later modify what we have done to make improvements. The great thing about CCWBRA builders is that each of us finds a way to approach our build and to innovate. There is no right way to do things, but it is a good idea to go to a race and to see what other builders have done, and to take from their ideas.
Best of luck with your build!
Keep in mind that the Tohatsu motor is bigger, heavier, and likely more powerful than the old OMC two-stroke motors.
Fred Allerton mentioned to me the risk of the motor coming off the transom while operating it. Jack and I took a look at the clamp to see if there’s a way of bolting the motor to the transom, but there’s no obvious way to do it. We’ll consider that issue later.
The wedge is another issue. I could probably come up with several slices of wedge to epoxy together if I spent a day in the garage with the tools that I have, but I’m not interested in doing it. I found a local (Fredericksburg, Virginia) woodworking shop to make one for me.
Andy,
I backed up my transom handles inside the side tank by epoxying a 3/4″ strip of wood behind the mounting points, similar to what Marty did. I would have preferred to drill and tap a piece of stainless steel as I did for my other mounting hardware points, but I was in a rush to get the deck on. I placed the handles centered 5″ below the point where the deck meets the carlins. The horizontal centerline of the handles is 5″ from the outisde of the hull sides. Those handle locations work perfectly.
The bow handle should definitely be backed well. I go for solid through-bolts on essential hardware, way more than I would trust wood screws. I often hang my boat in the garage to work on it and also like the assurance that I can tow anything or be towed without fear of pulling something off. I used threaded SS metal under the king plank for the bow handle and glued plates drilled for Uflex and classic shifter boxes. I can drill and tap new holes for any additional needs. I also added a vertical plywood strip for support behind the shifter.For pictures, details and a build blog, see teamloewen.com. I took a long rest after attaching the deck, but I plan to complete it soon.
Our boat has a vertical transom. Most power boats have an angled transom, so the OMC motor mount clamp is angled at about 10° from vertical (motor drive shaft). The wedge angle should be one that aligns the propeller shaft parallel with the bottom of the boat, but this angle should be fine tuned for optimum performance based on boat attitude, weight placement and much more.
I experimented with the motor wedge angle by making three (8 3/4″W x 6″H) wedges, 10°, 12° and 14°. The easiest way to measure the angles is to use two long aluminum rulers bolted together through the holes in the ends and measure with a protractor. Use one against the bottom and the other on the cavitation plate above the propeller. I setteled on 12° since it is the max and less can be adjusted on the motor bracket. The limiting factor is the width of the transom mount clamp (2 1/4″) on the motor, anything more that 12° won’t fit.
Another consideration is that when a wedge is added to the back of the transom, a wedge is needed on the front for theclamp screws and motor bolts to create a parallel surface. That distance limits us to a 12° wedge that has a thicknes of 2 1/4″ at the top. I modeled prototype clamp wedges from hardwood and then fabricated them from aluminum block material cut on my table saw with a carbide blade. You will also require wedges on the motor bolts on the transom inside. I can send pictures if you like.
Thrust brackets serve a different purpose than setting the prop shaft angle to the boat. A thrust bracket is used to reduce the stress to the top of the transom and provide support to the bottom of the motor so the transom does not flex. After several runs, I saw some contact of the motor against the transom. I plan to make a thrust bracket, but my temporary fix was to fabricate a small rectangular stainless steel plate for protection. It is 2″ x 4″ and has holes drilled to match the drain plug so the contact area slightly above the drain plug is covered.About the aluminum back plate, I added reinforcement blocks inside the tank where the cockpit sides meet the transom. I also added two vertical large triangular gussets on either side of the transom knee.
All of this is good input.
Given the difficulty of making a decent wedge without a table saw, radial arm saw, or power miter, plus decent carpentry skills, I think that CLC should offer them in various angles as an option. I’ll contact CLC and suggest it.
I agree with Marty on making the wedge. Also thank you everyone so far for their input on my questions.. I look forward to being on the water soon (I hope)
Andy
I sent an e-mail to CLC suggesting that they make wedges and offer them as an optional part. I’ll post the response here.
Andy, depending on where you are in NC, if you can get to Fredericksburg VA next friday, you can stay with me and ride up to Pasadena MD (near Baltimore) with me on saturday for the boat races.
Hey Marty, Thank you for the offer. However, I already have a pervious engagement for that weekend. But if not, I would have taken you up on offer.
Andy
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